[HN Gopher] How fast the days are getting longer (2023)
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How fast the days are getting longer (2023)
Author : antognini
Score : 589 points
Date : 2025-03-19 16:13 UTC (1 days ago)
(HTM) web link (joe-antognini.github.io)
(TXT) w3m dump (joe-antognini.github.io)
| porkloin wrote:
| I live just a couple hundred miles south of the arctic circle,
| and personally I hate the time of year where we "accelerate" into
| the equinoxes (equinoxii?). The rate of change is just too fast
| and too disruptive, and you _really_ see its effects on people.
| And then DST comes in and makes it even worse.
|
| The difference as you climb in latitude is really shocking. Even
| just another 3-400 miles south of here, the rate of change is way
| less severe.
|
| Anyway nice work and cool article! I've done some of these rough
| calculations myself before to plot out the change just to verify
| that I'm not insane for hating this time of year, and you did a
| way better job than I ever did :)
| jjtheblunt wrote:
| > equinoxes (equinoxii?)
|
| nox -> noctes, so equinoctes, if you're feeling Latin
| tcoff91 wrote:
| What makes you choose to live at such an extreme latitude? I'm
| always curious about what draws people to live in such places.
| porkloin wrote:
| I grew up here, so it's "home" so to speak. Well, technically
| my childhood home was a few hundred miles further south than
| where I am now (Fairbanks, Alaska). It's definitely an
| extreme climate to live in, but there are a ton of things to
| do outdoors, and although the daylight changes are very
| extreme, the excessive summer daylight makes that part of the
| year truly amazing.
|
| I do think the extreme polar opposites in daylight and
| temperature for summer and winter solstices contribute to
| people here being a little...unbalanced. But for a lot of
| people, the unique landscape, low population, and abundance
| of outdoor activities make it worthwhile.
| intalentive wrote:
| Nice typography. Classy.
| lars512 wrote:
| When living in Stockholm, I came to appreciate the various levels
| of twilight and darkness, rather than thinking of day and night
| so strictly. The sun being low on the horizon also scatters light
| across the sky in ways that are very beautiful and last much
| longer than sunrise and sunset in Australia where I grew up.
| piva00 wrote:
| Similar experience for me but probably even more extreme.
|
| I'm originally from Sao Paulo, Brazil, the Tropic of Capricorn
| almost cuts through the city itself. Sunrises and sunsets are
| very quick events, sitting somewhere to watch it would take
| some 30 minutes, and then darkness.
|
| Even after 10+ years of living in Sweden I still get mesmerised
| by sunrises and sunsets here, they last for so long and I get
| to be awed by the changing of colours, shadows, shapes, for
| hours. It's one of my favourite things to do during summers,
| just to be out somewhere by a lake with some friends, having
| food and drinks, and watching the endless twilight.
| Zanfa wrote:
| Having grown up around the same latitude as Stockholm, one
| thing I never realized until last year when visiting tropics is
| how my subconscious associates warmth with long evenings. Being
| used to summers where you could basically read a book outside
| at 11PM, it felt really weird to be outside in tropic heat, but
| complete darkness by 6PM.
| mdpye wrote:
| Catches me every time too. And it's so quick. You can go in
| to a shop to pick up a packet of crisps thinking it's
| daytime, but actually is quarter past 6, so you come back out
| and it's full dark!
|
| I'm in the southern UK, and I'd take our late-May/early-
| August "it's light while I'm awake and dark while I (should
| be) asleep" all year round if I could get it.
| jaggederest wrote:
| You could become peripatetic and seek out the spot of
| opposite latitude during the dark season. So you could have
| 15 hours of daylight, 12 hours of daylight, then 15 hours
| of daylight again. I've thought that with idle rich amounts
| of money I'd get a very large yacht and sail the pacific
| rim in time with the seasons, perpetual spring, summer,
| spring, summer.
| seizethecheese wrote:
| It does not seem that you need to be rich to accomplish
| this. Wintering in chile seems with decent planning
| wholinator2 wrote:
| We have different definitions of rich. It's not just the
| cost of living. It's also the time and to deal with the
| governments to allow this, it's having the money to spend
| the time, it's the job that allows this, it's the time
| away from family not being catastrophic for someone's
| wellbeing. Frankly, this is vastly infeasible for 99% of
| people. I'd easily consider the remaining 1% "rich" in
| some way
| mdpye wrote:
| It is a life goal, for sure! Not necessarily one I'll be
| able to reach, but we have to have stretch goals :D
| henrikschroder wrote:
| The first time I visited the tropics, I never realised how
| much I associated the dark with it being cold!
|
| We went for dinner in the afternoon, sun was up, it was
| blazing hot, everything normal so far. We had dinner while
| the sun set in a nice air-conditioned restaurant, so it was
| dark when it was time to leave, and I walked out into the
| tropical night and was _so confused_ why it was still warm
| and moist outside!
| thaumasiotes wrote:
| > Being used to summers where you could basically read a book
| outside at 11PM
|
| On the other hand, reading a book outside in normal daylight
| will hurt your eyes. The paper reflects too much light.
|
| Kindles solve this problem by being gray; I've never
| understood why Amazon went on to develop a "Paperwhite"
| model. Paper is too white!
| christopher8827 wrote:
| Depends. I lived in St Kilda where the beach faces east. The
| sunset / golden hour seem to start from 6pm to 9pm.
| dkdbejwi383 wrote:
| Up north in QLD, sunset seems to take about 15 minutes. Maybe
| a slight exaggeration, but it's very quick compared to London
| where I am these days.
| dietr1ch wrote:
| > When living in Stockholm, I came to appreciate the various
| levels of twilight and darkness, rather than thinking of day
| and night so strictly.
|
| In Chile you get somewhat long days and short days too,
| especially in the south, but instead of trying to be super
| precise about sunlight, the afternoon and night blend in and
| sort of crossfade. You end up with "8 de la tarde" (8 in the
| afternoon), and "6 de la noche" (6 at night) depending on the
| season.
| madcaptenor wrote:
| I think I have used "8 in the afternoon" even as close to the
| equator as Atlanta (~34 N). Our latest sunset is 8:52 pm,
| surprisingly late, because we are very far west in our time
| zone.
| madcaptenor wrote:
| Also: https://www.academia.org.mx/consultas/obras-de-
| consulta-en-l...
|
| 7/8/9 de la noche (vs tarde) is used by 60/97/100% of
| American Spanish speakers vs 1/16/97% of European Spanish
| speakers. I wonder if the difference is due to Spain's
| generally late sunsets.
|
| It would be interesting to redo this analysis with a corpus
| that indicates seasons though.
| TheSpiceIsLife wrote:
| Australia spans, what, 40 odd degrees of latitude.
|
| Where I'm at in Aus it's day light till 10pm at the summer
| solstice.
|
| No sun to really speak of at the winter solstice though.
| MarceliusK wrote:
| Growing up in Australia, you must have experienced quite a
| dramatic shift in how daylight feels when you moved
| madcaptenor wrote:
| "One of the more interesting features I hadn't appreciated before
| is that when you get close to the Arctic circle, the length of
| the days is essentially a zigzag, straight up from the winter
| solstice all the way to the summer solstice and back down again."
|
| I had noticed this too and wondered if it was exactly true, with
| the "zigzag" being straight lines - I thought there might be a
| simple proof of this fact based on some trig identities. There's
| not, because it's not true - the lines aren't exactly straight,
| even if you ignore solar refraction - but it's a very good
| approximation.
| pcthrowaway wrote:
| Not quite a straight line, but definitely a dramatic change
| (toggle the "Day/Night Length" view to see what I mean):
| https://www.timeanddate.com/sun/norway/longyearbyen
| alberth wrote:
| The graph gets crazy if you move the slider to be 66+ latitude.
|
| Is the graph correct at those extremes? Like North Pole?
| returningfory2 wrote:
| Yes. At these latitudes there are times of the year when it's
| always night or always day. This messes with the math such that
| the graphs look weird.
| kzrdude wrote:
| The graph looks like it's straight up interpolating between a
| sine curve and a tangent curve, it's so cool that way. (The
| calculations are more involved than that).
|
| Also signal analysis people will enjoy this natural system
| producing "almost pure" triangle and square waves. Nudge the
| plot to 66.55 degrees and it's at the most triangle wave point.
| :)
| antognini wrote:
| I'd say the graph's qualitative behavior is correct. Once you
| get to the arctic circle, there are singularities in the rate
| of change of the length of daylight.
|
| For example, if you're at the North Pole, the sun is below the
| horizon all winter, and then on the vernal equinox rises above
| the horizon and does not set again until the autumnal equinox.
| So, formally, the rate of change in daylight is zero all year
| long, except on the equinoxes when it is infinite. Any latitude
| above the Arctic Circle will have these kinds of singularities.
|
| In practice there are some corrections to the amount of
| daylight that I discuss at the bottom of the article, the most
| important of which is the effect of atmospheric refraction. If
| you were standing on the North Pole, you'd actually observe the
| Sun appear to rise some time before the vernal equinox.
| madcaptenor wrote:
| It's a shame we can't ask someone at the North Pole right
| now, a few days before the equinox, if the sun is up.
|
| For what it's worth, brr.fyi documents a sunset at the South
| Pole: (https://brr.fyi/posts/sunset) and a sunrise
| (https://brr.fyi/posts/redeployment-part-one)
| netsharc wrote:
| I guess the graph doesn't show the location of the sun even
| with daylight.
|
| In the extreme latitudes, you have short days where the sun
| just goes maybe 5 degrees into the sky and then down again:
| https://www.youtube.com/watch?v=Wzv_3LeA85c
|
| And days where the sun just circles around your location on the
| planet: https://www.youtube.com/watch?v=in0B1OQG3-M
|
| The opposite also happens, where the sun is below the horizon
| for months or weeks, and at the end of that period, it will
| inch towards the horizon, and you expect sunrise, but nope,
| it'll move furrther again... of course there'll be twilight
| (followed by night), but you might not see the orange ball of
| bright light for weeks or months.
| aeyes wrote:
| Unfortunate that the latitude is not allowed to be negative.
| kaffekaka wrote:
| Coming from middle of Sweden I remember the first time I spent a
| midsummers night in Lund in the south if Sweden and was
| astonished that the night was in fact dark! In my hometown, well
| below the arctic circle, the month of June is still constant
| daylight.
| hinkley wrote:
| I guess you have a lot of time to philosophize about the sun
| when you're knocking back your sixth cup of coffee for the day.
| zf00002 wrote:
| I always think of what time is sunrise where I am. Watching it
| get earlier/later every day by a couple minutes.
| bitmasher9 wrote:
| This phenomenon became very interesting to me after moving
| approximately 14 degrees further north (on the northern
| hemisphere) and experiencing not just shorter and longer days,
| but more rapid changes in day length during spring/fall.
|
| The impact this has on daily life is larger than I had
| anticipated, and in general reducing the intensity of the cycle
| is a selling point for cities closer to the equator. It's been
| nine years since my migration north, and I've only moved further
| north so this isn't a deal breaker for me. It's mostly something
| from my childhood and young adulthood that I took for granted.
| I'm now eagerly awaiting the day when my normal waking time is
| during dawn, which should be in early April.
|
| I'm still significantly further south than Northern European
| countries mentioned in this thread. Maybe life has more moves
| north for me in store.
| euroderf wrote:
| The seasonal extremes of daylight are so extreme up here in
| Finland that the cycle of night & day seems a bit less like a
| 24-hour cycle and a bit more like a 365-day cycle.
|
| An artifact of this is that my 5yo might not see a dark sky for
| the entire summer, unless we keep him up awake for the
| traditional Midsummer hangin'-out.
| hinkley wrote:
| What do you guys think about the movie Insomnia with Al Pacino
| and Robin Williams?
| euroderf wrote:
| I have not seen it. Should I ?
| munchler wrote:
| This is surprising. I had always assumed that the length-of-day
| function is essentially a sine wave everywhere on the planet, and
| that the derivative would thus be another sine wave shifted by 90
| degrees.
|
| When the day length is maximal/minimal (solstice), the day length
| change rate is near zero, and vice versa. That's still true in
| the more accurate model, even though the shape of the functions
| is more distorted.
| jampekka wrote:
| The calculated daylight even downplays the actual light at the
| high (or low) latitudes quite a bit. E.g. at latitude 60 there's
| a "nominal" midsummer night of about four hours, but it doesn't
| really get dark, as the light from the refraction is quite strong
| even with the disk not being visible.
| sunshinesnacks wrote:
| I think the section "Atmospheric refraction and the solar limb"
| near the end of the article addresses this.
| madcaptenor wrote:
| Not exactly; even after the sun is fully below the horizon
| there's some light. See the interactive graph - the times
| aren't long enough for twilight. But you can use a larger
| value of "a" in the equation above it to make that change.
| sunshinesnacks wrote:
| Yeah, you're right. Something like civil twilight, as you
| mentioned above, should get it closer to what is being
| discussed here.
| madcaptenor wrote:
| That's called "twilight". In the section "Atmospheric
| refraction and the solar limb" there's a modified sunrise
| equation with a variable "a" and text suggesting a correction
| of 50 minutes of arc there.
|
| If you replace 50 minutes with: - 6 degrees, you get the times
| of "civil twilight" (roughly speaking, when you don't need
| light outside). At 60 degrees north at midsummer the minimum
| altitude of the sun will be about -6.5 degrees so almost all of
| the nominal night is civil twilight. - 12 degrees is "nautical
| twilight" (horizon clearly visible) - 18 degrees is
| "astronomical twilight" (sky is dark enough for all
| astronomical observations).
|
| (It's possible that those are defined as 6 degrees + 50
| minutes, etc.)
| qwertox wrote:
| And it's not just "sunset + X minutes" where X would be a
| constant. In the winter this X is much shorter than in the
| summer.
|
| For me X is then a "travelling" value which in the winter is at
| 1/3 between sunset (0deg) and civil dusk (-6deg), and in the
| summer it goes up to 2/3. Calculated as the moment when the
| blinds go down.
|
| I'm using https://astral.readthedocs.io for this.
| madcaptenor wrote:
| What's the reasoning behind using a different value in winter
| than summer? Your winter value roughly corresponds to -2deg,
| your summer value to -4deg.
| qwertox wrote:
| You made me check the code and actually I have it the other
| way around (and with different ratios, winter=-6deg,
| summer=-2deg), because else the blinds would go down too
| late in the summer (after 22:00).
| jameshart wrote:
| Even in the UK around 51-52degN you get a few nights around
| midsummer where it never truly gets dark - no darker than
| 'nautical twilight' at least.
| pcthrowaway wrote:
| I just pulled up Whitehorse, Yukon (at the 60th parallel), and
| sure enough, the longest day of the year is essentially always
| day: https://www.timeanddate.com/sun/canada/whitehorse. Almost
| 5 hours of civil twilight, but civil twilight is still daytime
| in my book.
| Sharlin wrote:
| Twilight is caused by scattering rather than refraction.
| There's sunlight bouncing around in the atmosphere, keeping the
| sky non-black even after sunset.
| MarceliusK wrote:
| Even during the "night," the sky stays illuminated enough that
| it never truly feels dark. It definitely challenges the idea of
| what nighttime means and makes the summer feel almost magical,
| but I imagine it can also mess with your sleep patterns!
| 1ewish wrote:
| What am I missing here? It states:
|
| > On the equator, every day of the year is exactly 12 hours long
|
| But surely that is not true, as the Earth's rotation is tilted.
| Is this supposed to be a year round average? Despite calling out
| more advanced corrections one can make, this doesn't seem to be
| mentioned anywhere?
| xbmcuser wrote:
| In Garissa, Kenya, which is almost exactly on the equator, the
| day length varies between 12 hours 6 minutes and 12 hours 9
| minutes. So it is 12 hours if you are rounding to hours.
| madcaptenor wrote:
| Pontianak in Indonesia is right on the equator (I'm seeing 1
| minute 14 seconds south latitude at Wikipedia).
|
| timeanddate.com gives
| (https://www.timeanddate.com/sun/indonesia/pontianak)
| variation between about 6.5 minutes and 7.5 minutes above 12
| hours, long at the solstices and short at the equinox. The
| difference is due to the sun setting vertically at the
| equinoxes and at a slight angle to vertical at the sunset.
| globular-toast wrote:
| It's true. Highly recommend getting a globe in your hands to
| convince yourself about stuff like this. Close one eye, pretend
| you're the sun and observe the effect the tilt has and how it
| has no effect on the equator (apart from changing the angle of
| the sun; interestingly the sun's path alternares between being
| in the north sky and being in the south sky).
|
| You'll also be able to understand time zones and great circles
| (flight paths) better with a globe.
| 1ewish wrote:
| Ok thank you! I think I can see how I am wrong now and why it
| doesn't actually make a difference.
| tshaddox wrote:
| To be clear, the days and nights are still not exactly 12
| hours because the Earth does not take exactly 24 hours to
| rotate.
| staplung wrote:
| It's true that the Earth does not usually take _exactly_ 24
| hours to rotate, it 's only 24 hours _on average_ over the
| course of the year. However, the difference is only ever
| off a few seconds at most. Those seconds pile up across the
| days around perihelion and aphelion amounting to several
| minutes cumulatively but that doesn 't affect the length of
| the day, only the amount that solar noon differs from noon
| on the clock.
|
| The reason that days are a few minutes longer than nights
| at the equator is due to atmospheric refraction which makes
| the sun visible a little before it actually has "risen" and
| similarly, keeps it visible a little after it has "set".
| NorwegianDude wrote:
| It's always interesting how it affects how people think about the
| day. If you look outside and it's dark then it's easy to think
| that the day is basically over, even though the time might say
| otherwise.
|
| I really appreciate the long winter nights and long summer days
| in Norway. Being able to wake up to the sun as early as 04 and
| enjoy it until after 23 is great, and the UV is only high during
| the middle of the day. Long summer days are awesome. Long winter
| nights are probably not as appreciated, but I enjoy those too.
| MarcelOlsz wrote:
| I'm trying to find the darkest corner of the earth to chill in
| so I can actually get some work done. I can't get anything done
| when the sun is out and people are out and about. Maybe I'll
| move to that Italian village that has the giant sun mirror
| thing.
| kccqzy wrote:
| I personally like extremes. My ideal scenario would be a dark
| room where I can get work done, and then every hour or so, I
| take a five-minute break outdoors in direct sunlight.
| hollerith wrote:
| I spend most of the day in a fairly dark room, but make
| sure to get at least 20 minutes of sunlight on my bare skin
| and eyes every other day -- but it's not because I like
| extremes: it is because sunlight is good for me, but LED
| light bulbs are bad for me or at least they are if they are
| of typical brightness and they are on most of the day.
| munificent wrote:
| Seattle says hi.
| MarcelOlsz wrote:
| I was under the impression that Seattle was ultra sunny.
| magneticnorth wrote:
| July - September, yes, we have oppressive sunshine.
|
| Spring/fall tend to be cloudy & rainy, and November to
| February-ish is referred to as "the big dark" - the days
| are short and the sun is low and obscured by clouds when
| it's above the horizon. Sounds like you'd get a lot done
| then (as do many people here).
| dowager_dan99 wrote:
| Calgary, AB enters the chat: Calgary, Alberta, is
| considered the sunniest city in Canada, with an average
| of 333 sunny days and 2,396 hours of sunshine annually.
| keybored wrote:
| Rjukan, Norway. Dark half the year, cheap real estate and
| comes with mirrors.
|
| https://www.bbc.com/future/article/20170314-the-town-that-
| bu...
| MarcelOlsz wrote:
| Ah that's the one I was thinking of. I'm seriously
| considering it.
| munificent wrote:
| Fifteen years ago, I moved from Orlando to Seattle, and almost
| 20 degree change in latitude. On top of that, Orlando is
| famously hot and sunny and Seattle famously cold, cloudy, and
| rainy.
|
| Despite that huge change, I adapted to the new climate just
| fine. I don't mind the gloom or the cold. The six months of
| gray skies don't get my down like they do a lot of people.
|
| But even after a decade, I still haven't gotten used to how
| much the day length changes. Every summer my brain keeps
| expecting the sun to go down any second now while it sits up
| there near the horizon giving an extra two hours of daylight.
| Every winter it feels like the sun disappears too early.
| nostromo wrote:
| Seattle's climate is a joy.
|
| It's rarely super hot or super cold like a lot of places.
|
| You get these ridiculously long summer days that last
| forever. It's perfect for athletics and hiking and spending
| time on the water.
|
| And likewise you get these wonderfully wet and dark winters
| which are perfect for life's other joys: coding, reading,
| playing video games, boardgames, drinking coffee, etc.
|
| I love places like San Diego / LA but I wouldn't want to live
| in a place that is always a perfect summer day.
| mikepurvis wrote:
| I was in Seattle Sept-Dec of 2008 on an internship and I
| remember feeling some of this. Based on what people had
| said, I was geared up for four months of a soggy, misty
| mess, but it wasn't that at all-- the autumn there was
| splendid, with tons of breezy, cool days where the sun
| still shone, with the trees around my place in Madrona
| showing brilliant colour for weeks on end.
| bombcar wrote:
| San Diego is months of June Gloom and other Seattle-
| reminiscent weather, and some sunny days.
|
| Unless you're inland, where it's ninety billion degrees in
| the shade half the year.
|
| Nice place.
| rconti wrote:
| That's much of the west coast (west of the cascades). I
| moved from Seattle to the Bay Area, and it's basically the
| same weather except somewhat shorter summer days and winter
| nights, WAY more sunshine, and generally about 10f warmer.
| Except in the summers where these days it seems like
| Seattle has more 95+ degree days than the peninsula does.
| screye wrote:
| Definitely unpopular opinion.
|
| I love 4 seasons. But the weather and day length make for a
| difficult half-year from Oct - Mar. The NE corridor has
| some of these traits, but it was a lot easier to deal with
| there. In the NE, rain & grey-skies aren't as persistent.
| In Seattle, a month can go by without seeing the sun.
| connicpu wrote:
| The downside of the historically mild climate is a lot of
| older homes weren't built with energy efficiency in mind
| and now in 2025 we have to deal with that inefficiency on
| our energy bills :'(
| muyuu wrote:
| It's the same in the UK vs Southern Europe and Japan where
| I've lived before. People complain about the wet weather, but
| it's not that IMO what really gets to you, it's the dark
| winters with so little daylight compounded with the abundance
| of cloudy days.
|
| Temperature-wise, most of the UK is actually quite moderate
| compared to central Europe. It's winter darkness that gets to
| you.
| fifilura wrote:
| To put it in perspective, Paris is further north than
| Seattle.
| porkloin wrote:
| I think what's fascinating about it is the daylight changes
| you experienced in the 20 deg latitude change you experience
| from Orlando to Seattle are dwarfed by the changes from a ~15
| degree latitude change from Seattle to Anchorage. By the time
| you're getting close to the pole, you can see huge
| differences in solstice minimum/maximum sunlight by moving
| just a few hundred miles north or south.
| jghn wrote:
| I really struggle with this at daylight savings switches when I
| work in offices where I can see a window. It takes me a couple
| of weeks to adjust. In one direction I find I work later than I
| intended. In the other direction I find myself ready to leave
| and realize it's only 4:30
| dullcrisp wrote:
| I tend to lean into it, though that's of course not an option
| for most people.
| intothemild wrote:
| As someone who moved to Norway. The only thing that's strange
| to me about the length of day/night... Is that we do daylight
| savings here.
|
| Why? What help does it make adding one extra hour to the start
| of the day, when the day lasts like ~4 hours.
| latexr wrote:
| Could be so the time is better synchronised with the rest of
| Europe, which is relevant for business reasons. I seem to
| recall reading recently about some other country doing
| exactly that (though it wasn't Norway).
| madcaptenor wrote:
| Mexico used to have daylight savings even though they're
| close enough to the equator that it doesn't make sense -
| that's to harmonize with the US. When they did have
| daylight savings time, though, the state of Sonora didn't,
| because it borders Arizona, which doesn't.
| kevin_thibedeau wrote:
| For economic harmony with EU.
| matsemann wrote:
| Yeah, I hate it. I don't need more light in the morning, I'd
| rather have that as a bit more visibility when skiing after
| work. And it anyways only takes like two weeks before the
| gained light in the morning is gone.
|
| https://www.timeanddate.no/astronomi/sol/norge/oslo
|
| 25th of october day is from 08:21-17:39, 26th of october from
| 07:24-16:36 after dst, and then 17th of November we're at
| 08:19-15:43 (so back to dark mornings). I'd rather the 17th
| have light until 16:43.
| bastardoperator wrote:
| My buddy went to Norway and was super upset because the sun
| never set in the part of Norway he was staying in and he had no
| idea it would be daylight almost the majority if not the entire
| day. He also said his Norwegian family was getting upset with
| him because he wasn't sleeping and keeping everyone up due to
| his lack of day/night reference.
| porkloin wrote:
| I live at ~64 deg latitude in the USA (Alaska) and 100% agree
| with everything you said. The timing of sunset has such a
| profound effect on when you consider the day "done". In Dec
| it's painful to haul myself outside at 5 or 6 PM since it's
| "night time" already. Meanwhile in June, at 11PM/23:00 when
| it's still bright out I have to remind myself to home and go to
| bed so I'm not a tired wreck at work the next day :)
| kccqzy wrote:
| Very interesting discussion! I did a less theoretical approach a
| while ago to calculate the same thing: I just go to
| timeanddate.com, find the city I'm interested in, go to its sun
| page (example for New York
| https://www.timeanddate.com/sun/usa/new-york), and find the table
| that shows the difference in daylight minutes per day. No math or
| programming needed, just copy-paste and some buttons in Excel.
|
| Not as satisfying as a derivation here, but a quicker way to get
| the answer.
|
| EDIT: I did a spot check for Rovaniemi, Finland. This city is far
| north enough that the sun is up all day (66.5 degrees). But the
| graph on this page seems to be a little bit off: it requires an
| even higher latitude for that to show up.
| mig39 wrote:
| Moving to Northern Canada has made me really really appreciate
| Spring. Going to work in the dark then going home in the dark is
| exhausting. I'm at 56oN. I imagine it's worse for those who are
| even further North.
| neilwilson wrote:
| Scotland then :-)
| keepamovin wrote:
| Nice iambic pentameter in that title. How fast
| the days are getting long and so The summer rains are
| melting all the snow
| yu3zhou4 wrote:
| Thanks for posting! It's a good read, quite Bartosz Ciechanowski
| esque
| antognini wrote:
| Thank you! That's high praise! :)
| blackeyeblitzar wrote:
| For the Americans, daylight savings time also changes the
| perception of how the days are getting longer.
| dkdbejwi383 wrote:
| DST exists in a lot of the rest of the world too
| frankus wrote:
| The whole "6am sunrise and 6pm sunset every day of the year"
| thing at the equator is kind of mind blowing.
|
| Another maybe counterintuitive fact is that (to a reasonable
| approximation) everywhere on earth gets the same number of hours
| of daylight over the course of a year.
| infinitifall wrote:
| Funny because growing up in the tropics I thought sunset and
| sunrise were synonymous with those times of the day, and
| learning people in other parts of the world experienced
| shrinking/lengthening day/night cycles was mind blowing. You
| mean it's 8PM in the _night_ but the sun 's still in the sky?
| n_ary wrote:
| What do you mean 08:00PM. We have enough sunlight up into
| 09:47PM(21:47) during mid to late summer and darkness falls
| after 10:30PM(22:30).
|
| Winter is... Sunrise at 08:12AM and Sunset by 04:00PM(16:00).
|
| You can technically use this info to guesstimate my location
| ;)
| dylan604 wrote:
| Since you used a 12-hour clock by default, upper mid-west
| US?
| tempestn wrote:
| I'd guess Canada given latitude and the fact that both
| formats were given.
| henrikschroder wrote:
| I was at a wedding in Sweden near midsummer with a lot of
| international guests. They were quite surprised to get out of
| the reception dinner at 10pm and see that the sun was still
| up. We were below the arctic circle, so no midnight sun, but
| it doesn't really get dark during the night, you get an hour
| or two of twilight, and then the sun rises at 2am again.
| anthomtb wrote:
| I travelled to Stockholm from North America a few decades
| ago, right around midummer. Worst jetlag of my life.
|
| The problem was that 20 hours of daylight, especially
| having 2:30 AM feel like 6:30AM. It was impossible to get
| an adequate amount of sleep. The paper thin curtains in the
| cheap hotel where I stayed did nothing to block out the
| light.
|
| If I am ever in that part of the world at that time of year
| again, I will be bringing a sleep mask and seeking out a
| hotel with proper blackout blinds or curtains.
| dylan604 wrote:
| I would have thought that for places that close to the
| arctic circle would be a national crime to not have full
| black out curtains. The difference being the punishment
| based on what nation the crime was committed.
| BurningFrog wrote:
| When you live there you get used to sleeping in daylight.
|
| That's not an excuse to not provide black out curtains at
| a hotel for international guests, but I guess people just
| don't think about it.
| widforss wrote:
| Let me tell you about Svalbard curtains. Dish soap and
| aluminum foil.
| DiggyJohnson wrote:
| Dish soap?
| widforss wrote:
| To make it stick
| flurdy wrote:
| You can just bring or buy some pop-up travel blackout
| blinds made for babies. We used those with great effect
| when visiting my parents' summer house in Northern Norway
| in the summers when the kids were young.
|
| Bonus, they now work as great blackouts in my home office
| for video calls when I do not want sunshine and clouds to
| change my green-screen effects etc.
| globular-toast wrote:
| I'm not sure if I should recommend the film _Insomnia_.
| You 'll either like it because you can relate or might be
| traumatised all over again!
| globular-toast wrote:
| I live in the south of England and experienced this in
| Scotland. I was trying to get somewhere to pitch my tent
| but rapidly running out of light, or so I thought. It was
| the height of summer and it just never really got dark.
| Maybe England isn't as different as I think it is, but it
| was strange to find my assumption that night=dark was quite
| wrong.
| hnuser123456 wrote:
| Yes, though a location at 45 degrees N/S only gets 70.7% as
| much sun power per area due to not being perpendicular to the
| sun's light, and even less on the ground due to extra
| atmosphere to pass through.
| frankus wrote:
| Appropriately enough, that "everywhere on earth gets the same
| number of hours of daylight" fact came from a solar system
| salesperson, who didn't go out of his way to emphasize the
| atmospheric effects here at ~49degN.
|
| The silver lining is that our longest days are often our
| sunniest.
| hinkley wrote:
| When we were in Hawaii I think the only reason we caught the
| sunset is because we were less than 400 yards from a beach. By
| the time you know the sun is going down you are about to be in
| the dark.
|
| Movies about vampires in the Arctic Circle are fun but vampires
| at the equator would be more terrifying for the humans at dusk
| and for the vampires at dawn.
| godelski wrote:
| > The whole "6am sunrise and 6pm sunset every day of the year"
| thing at the equator is kind of mind blowing.
|
| You can take this further. Look at weather and seasons. Here's
| Nairobi's yearly averages[0]. You can see that both temperature
| and precipitation are fairly consistent. On the other side of
| the continent Libreville[1] has a bit more precipitation
| variance but still low temperature variance. Let's got to South
| America with Macapa[2] and Quito[3] and let's keep going and
| land in Kuching[4].
|
| Essentially in these regions, there are no real seasons. At
| least in the sense that many think of them. Things do change,
| but winter isn't that different than summer.
|
| I know there are variances, but the scale masks a bit of what's
| going on. So let's look at London[5], Osaka[6], Auckland[7],
| Los Angeles[8] (often joked at for having no weather),
| Seattle[9], and Oslo[10]. As you can see, these are _extremely_
| different situations. It even has large effects on how people
| think about weather, time, and other things.
|
| It's funny how what is so obvious and normal to some are
| completely different to others. Sometimes seeming as if we live
| in different worlds. In some sense, we do, and I think we often
| forget that. [0]
| https://www.timeanddate.com/weather/kenya/nairobi/climate
| [1]
| https://www.timeanddate.com/weather/gabon/libreville/climate
| [2] https://www.timeanddate.com/weather/brazil/macapa/climate
| [3] https://www.timeanddate.com/weather/ecuador/quito/climate
| [4]
| https://www.timeanddate.com/weather/malaysia/kuching/climate
| [5] https://www.timeanddate.com/weather/uk/london/climate
| [6] https://www.timeanddate.com/weather/japan/osaka/climate
| [7] https://www.timeanddate.com/weather/new-
| zealand/auckland/climate [8]
| https://www.timeanddate.com/weather/usa/los-angeles/climate
| [9] https://www.timeanddate.com/weather/usa/seattle/climate
| [10] https://www.timeanddate.com/weather/norway/oslo/climate
| balderdash wrote:
| I lived in East Africa for a while and you'd get kick out of
| the way time is referred to in Swahili, "midnight" is 6am, and
| the first hour of the day 7am etc. makes a ton of sense when
| sunrise is around the same time each day!
| BurningFrog wrote:
| There is the same number of hours of daylight, but near the
| poles you sleep through a lot of those hours in summer. So you
| _experience_ far fewer hours of daylight.
|
| Another mind blowing thing about the equatorial sun is seeing
| it above you! Where I grew up, the sun is never higher that 30
| degrees.
| muzani wrote:
| Living at the equator most of my life, it's actually funny how
| schedules are messed up when the sunrise is half an hour
| earlier or later. Traffic becomes chaotic because some people
| insist on getting home before sundown, or things like people
| becoming uneasy that the school starts before sunrise.
|
| Weather is fun too, because it changes by +/- 3 degrees
| throughout the year. The heat makes my bedroom door expand. We
| had an argument with the housing developers because we had
| custom doors that didn't fit. But turns out it was passing all
| the tests when they ran it, and not in hotter periods of the
| year.
| account42 wrote:
| > Another maybe counterintuitive fact is that (to a reasonable
| approximation) everywhere on earth gets the same number of
| hours of daylight over the course of a year.
|
| Not the same amount of _usable_ daylight though as the amount
| you have to waste to get a decent amount of sleep all year
| around varies by latitiude.
| MarceliusK wrote:
| Kind of poetic how nature balances things out in the end.
| LeoPanthera wrote:
| DST really bothers me. I actually have a wall clock set to local
| solar time, so that I can quickly see what time it "really" is.
| For some reason I've always been very sensitive to when sunrise
| and sunset is, and having them offset makes my brain feel weird.
| przemub wrote:
| You should live in London! UTC, time zone and solar time all
| close to each other :) Now if we got rid of that pesky DST...
| keybored wrote:
| Yeah I have to say the north of Europe is bad folks. Winters are
| terrible. You just go to work/school in the dark and come home in
| the dark. There's also less snow now than twenty years ago which
| means even less light.
|
| In the summer it's light outside for more hours than you are
| awake. Okay wow, so what? It's a nice novelty. But it doesn't
| make up for it. Not remotely.
|
| Midsummer is a sad time because now I know that I will lose X
| minutes every day of light.
|
| Using DST is just the extra bit of small cruelty on top of that.
| madcaptenor wrote:
| DST only really makes any sense at mid-latitudes. If you go
| close enough to the poles it just seems silly to move around
| that hour - does it really matter if the sun is up from 2 AM to
| 10 PM or from 3 AM to 11 PM?
| henrikschroder wrote:
| DST is completely silly as far north as the Nordics. The rate
| of change in daylight is so rapid around the equinoxes, that
| the effects of DST are erased in less than two weeks. It's
| completely useless.
| iteratethis wrote:
| I see the problem differently, although in a useless way.
|
| The shortest day still has 7-8 hours of daylight. There's no
| shortage of daylight, we have too much work.
| zokier wrote:
| Shortest day where I currently live has 5h49min of daylight.
| My childhood home had full month of no daylight. You
| definitely have shortage of daylight as you move towards
| poles.
| Aaargh20318 wrote:
| I'm in the Netherlands (around 52oN) and in my opinion DST is
| counter productive, especially considering the effects of
| global warming.
|
| Summers are getting hot, to the point where it's uncomfortable
| to be outside while the sun is out. It's barely tolerable in
| the shade, assuming you don't move too much. It only gets
| comfortable outdoors after sunset. During workweeks this means
| you barely have any usable outdoor time before you need to go
| to sleep. It also means your bedroom has little chance to cool
| down before you need to go to bed. Summer nights are nice when
| you're outdoors, but DST robs us of the best hours to be
| outside.
|
| If we're going to move the clock in summer, we should move it
| backwards another hour. It would mean 2 more hours (compared to
| the current DST) of nice summer nights, instead of extra hours
| of scorching sunlight. I suggest we call it 'Moonlight Saving
| Time'.
| PhilipRoman wrote:
| Screw half measures like DST, as an office worker I have a
| dream of working in winter from 16:00 till 24:00, sleeping from
| 01:00 till 09:00 and enjoying my sunlight for the rest of the
| day. I would fit right in working remotely for a company
| somewhere in the Far East.
|
| Of course, the worst part is that often in winter we don't get
| sunlight at all, only a gray-ish cover of clouds in the sky :(
| divbzero wrote:
| A closely related follow-up blog post could be titled: "How Long
| Twilight Lasts".
| tasuki wrote:
| I'd love to read that!
|
| It depends on the latitude for sure, but also I think on the
| time of the year?
| madcaptenor wrote:
| Play with timeanddate.com's times. It gives the total amount
| of civil twilight for the day (which is split in half). For
| example at Atlanta
| (https://www.timeanddate.com/sun/usa/atlanta) there's 58
| minutes per day at the summer solstice, 55 at the winter
| solstice, and 50 at the equinoxes. As you go poleward those
| numbers increase but it's always summer solstice > winter
| solstice > equinox. This is basically down to the angle
| between the sun's path and the horizon and I think I get why
| that would be different in summer than in winter but I can't
| get my head around the fall/spring bit.
| tasuki wrote:
| Ah yes, a very helpful link!
|
| I think the angle under which the sun rises/falls is
| steeper in spring/autumn. And summer/winter is less steep.
| And in summer it bends upwards when under the horizon,
| making summer sunset longer than winter. I'm not sure if
| these are the right words - it sounded better in my head!
| madcaptenor wrote:
| I think you're right about the angles but I can't picture
| it well enough to understand why.
| antognini wrote:
| You'd be able to do it based on the math in the article.
| Civil twilight lasts from sunset until the Sun is 6deg below
| the horizon. So in the spherical law of cosines in the
| article, you'd just set a to be -6deg instead of 0.
| appleorchard46 wrote:
| (note - only semi-relevant)
|
| While southern Florida is hardly at the equator, living here has
| really highlighted how northern-hemisphere and temperate-centric
| the online sphere - tech in particular - tends to be.
|
| We don't get spring/summer/autumn/winter so much as rainy and dry
| season; heat pumps are irrelevant; natural disasters come in the
| form of hurricanes, and weather is either sunny or stormy; the
| days don't change in length much; and so on and so on.
|
| It's a bunch of little things, but it's been surprising to me how
| often they come up in discussions, and just how rare
| (sub)tropical-specific problems and topics are in comparison. It
| makes me wonder what it's like to live somewhere even further
| removed from the natural world of the north.
| speakspokespok wrote:
| July 5th through September in Seattle are a dream; incredibly
| long days, dry but not too hot. The sun never sets. I've been a
| lot of places on the planet and PNW summers are uniquely great.
|
| However, during the winter it's dreary, it's dark by noon, and
| every year around October the raven comes tapping at my chamber
| door.
|
| July of 2020 I left and went south to Central America. That first
| 'winter' I kept waiting for my annual S-A-D season to start. It
| didn't. The second 'winter' was worse because I reasoned the lst
| time could have been endorphins keeping me going. I was really
| expecting any day for the depression to start. And again, it
| didn't. December and January felt normal. That very consistent
| 7am it's bright sunny day and at 7pm it's dark night all year is
| helpful.
|
| Quite literally, I never intended to return to Seattle, but with
| the recent economic turmoil it worked out that way. S-A-D season
| kicked off like usual, even with the 10,000 IUs of Vitamin D.
|
| Without a job I moved to Eastern Washington, and within a month I
| was doing better, life got easier and the future was far less
| inscrutable. I have the energy to do the work, and after an angry
| or sad thought the follow-up thought is "that was a bit
| dramatic". That's a sign every year that things are on the up-
| swing.
|
| Many people love and appreciate the Seattle climate just as it
| is; I don't know really anyone that reacts quite as severely as I
| do to it. Not being in Seattle weather means I get 6 more months
| of life every year. It kills me how much time I wasted trying to
| 'fix myself' in a place I just wasn't meant to be.
| silisili wrote:
| I've only ever been to Seattle to visit in summertime, and
| largely agree with everything. It's probably the prettiest
| place I've ever been (weather/greenery wise). But I already
| know I can't handle the greyness of the other seasons. Real
| shame.
|
| Even living in the south, the 3 or so months of SAD feel like
| an eternity. I don't know how anyone could stand an even longer
| period.
| sepositus wrote:
| I live within a short distance of the western side of the
| Cascades (I don't want to dox myself any further). Meaning I'm
| on the eastern side. The difference in weather between the two
| sides is pretty shocking. During the winter, I often look to
| the west and see a solid sheet of clouds.
| frogulis wrote:
| What's different about the eastern part of the state? Is it as
| simple as having less rain and clouds to block out what
| sunlight there is?
| speakspokespok wrote:
| The western half of the state is close to the ocean with warm
| ocean currents, so you get a lot of moisture. However the
| Cascade Mountains split the state N and S. Windward side is
| Seattle side, so all the rain stays there.
|
| Eastern Washington then is in the rain shadow. Actually I
| think it's high desert - there's very little annual cloud
| cover.
|
| The Cascades go all the way to California so this pattern
| applies to Washington, Oregon, and maybe Nevada.
|
| In the context of my original comment, I can only speak from
| an experiential sense. I think it's the strength or frequency
| of the sunlight, maybe the UV, is what makes the difference.
| pcthrowaway wrote:
| We have this same pattern in Vancouver and a good chunk of
| British Columbia as well, though this winter which just
| ended was the mildest of the 11 years I've been here
| jader201 wrote:
| Something that is still crazy to me, regarding time zones, is
| that my hometown (where my mom lives and we visit frequently) is
| about 1.5 hours to the west, one timezone over.
|
| When I'm taking to her on the phone in the evening, we'll be
| talking about it getting darker.
|
| The difference in the sunset 1.5 hours away in another timezone:
|
| About 9 minutes.
|
| This equates to my evening daylight lasting 51 minutes than hers,
| and her daylight in the mornings starting 51 minutes before mine
| (in our respective time zones).
|
| Which seems to negate the whole effects of daylight saving time
| for one of us.
|
| Of course this is exacerbated even more if you're across the
| border of a timezone from each other (which I pretty much live on
| the western border of ET).
| supernova87a wrote:
| There is a handy rule of thumb called the "rule of 12ths", used
| in seamanship / ocean navigation / tidal calculations (maybe it
| is used elsewhere too, this just happens to be where I recognize
| it from). I think it can apply to solar, seasons, etc. -- well,
| anything sinusoidally cyclical -- as a useful mental model:
|
| If you divide half the phase of a cycle (peak to trough) into 6
| hours duration or whatever appropriate unit, like 6 months, i.e.
| x-axis --
|
| then going down from the top of the peak (or up from trough), the
| amount of y-axis change in each unit/hour is:
|
| Hour (or month #): amount of change vs. peak-trough total (i.e.
| total = 2*A)
|
| 1: 1/12
|
| 2: 2/12
|
| 3: 3/12
|
| 4: 3/12
|
| 5: 2/12
|
| 6: 1/12
|
| For us, the peak / trough are: June 21 to December 21, and the
| x-axis is 1 month units. And assuming maybe a 2 hour peak-to-
| trough difference in daylight time y-axis (depends on latitude
| you live of course), then each 1/12th equals 10 minutes.
|
| So these days (late March) we are in the middle of the fastest
| decrease part, and each month we gain 30 minutes of daylight. Or,
| each day we are seeing sunset get pushed by like 1 minute.
|
| see: https://en.wikipedia.org/wiki/Rule_of_twelfths, the diagram
| explains it better of course
| madcaptenor wrote:
| Restated in mathier language: sin(30 degrees) = 1/2 and sin(60
| degrees) isn't that far from 5/6.
| widforss wrote:
| That was a fascinatingly good approximation of sin().
| soloFU wrote:
| All days are 24 hours except the one when we "make days longer"
| which is only 23 hours.
|
| Then we "make days shorter " resulting in a 25 hour day.
| mkoubaa wrote:
| Fasting the month of Ramadan when it lands in March or September
| is always the most interesting for this reason. You have to
| change how you plan your daily routine as the month goes.
| esalman wrote:
| The writer had to attend a standup with a colleague in Norway to
| realize this and write an article. Funnily enough, as a Muslim I
| get reminded about this annually during Ramadan, which is right
| now.
|
| First of Ramadan this year coincided with March 1, and it was a
| 12:45 hours of fasting from the first light of dawn to sunset at
| my location, also near Los Angeles. Today it's going to be 13:15
| hours long, and by the time last of Ramadan rolls in around the
| end of March, it will be 13:37 hours.
|
| Ramadan is observed following the lunar calendar, which is
| shorter than solar- based calendars by about 10 days. A winter
| Ramadan is short and easy in the northern hemisphere and we will
| have the shortest days in 2031. 2047 it's going to be middle of
| summer, so the hardest.
|
| In case you ask, well what about places where sun does not set?
| When do you have your Suhoor (meal before dawn) and iftar
| (breakfast meal at sunset)? Opinions differ, but people usually
| follow the more realistic time of sunrise and sunset at a
| reference location. My brother in law was in Sweden few years
| back and he used the time of Mecca as reference.
| speakspokespok wrote:
| So you have to plan your daily routine around the rules of
| Ramadan, and their interpretation differ by your location and
| from year to year?
| rat9988 wrote:
| My routine changes depending on location and the year anyway.
| travisjungroth wrote:
| Solar calendar user, meet lunar calendar user.
| thaumasiotes wrote:
| I'm not seeing how the time of sunrise and sunset differ
| according to whether your calendar follows the sun or the
| moon. Ramadan wanders through the solar year, sometimes
| occurring in the summer, sometimes in the winter, because
| it is scheduled according to the lunar cycle. But the fact
| that Stockholm has a lot more daylight during summer than
| Mecca does is just a consequence of the layout of the
| Earth. They both have summer _at the same time_. The
| effects are what 's different.
| travisjungroth wrote:
| If you use a solar calendar, the difference would only be
| by location. Solar calendar users already experience
| that. It applies for day-to-day stuff, but I actually
| can't think of any events explicitly tied to
| sunrise/sunset in a Western/Christian calendar. So you
| really need that to experience the full extreme, which
| Ramadan has.
|
| Jewish holidays have that too, with the new day starting
| at sunset. But the calendar is lunisolar, so it wobbles
| buts doesn't drift. Islamic calendar has maximum
| differences.
| bloppe wrote:
| That's why people who use lunar calendars tend to live
| closer to the equator, where the annual effects of the
| Earth's tilt are negligible and the lunar cycle is much
| more noticeable
| achierius wrote:
| Before the modern era, Christian countries also
| demarcated their hours according to sunrise and sunset;
| even today, Catholic and Orthodox monasteries and
| seminaries use these for the Liturgy of the Hours.
|
| https://www.usccb.org/prayer-and-worship/liturgy-of-the-
| hour...
| antasvara wrote:
| >Ramadan wanders through the solar year, sometimes
| occurring in the summer, sometimes in the winter, because
| it is scheduled according to the lunar cycle.
|
| To be honest, that's the difference people are talking
| about (at least to my understanding). Because Ramadan
| follows a lunar calendar, the sunrise on the first day of
| Ramadan in Stockholm could happen anywhere from ~3:30am
| to ~8:45am depending on the year.
|
| If I were using a lunar calendar as my actual calendar,
| the first day of the year would also have a sunrise time
| that varied significantly.
| walrus01 wrote:
| The start and the end of ramadan (the month) are based
| entirely on the lunar calendar, and the islamic
| authorities that your particular branch of the faith
| sighting the moon by eyeball, but the length of time per
| day that you're obligated to fast are based on sunrise
| and sunset, which is obviously solar.
| Ozzie_osman wrote:
| Yes! You should also look into how pro athletes handle the
| logistics of fasting and competing (eg Kyrie, Mo Salah, and
| many others).
| madcaptenor wrote:
| I saw some things recently about how Hakeem Olajuwon fasted
| during Ramadan and generally his performance was just as
| good during Ramadan as during the rest of the season, which
| is really impressive.
| esalman wrote:
| Yeah. Just trivial Muslim problems.
|
| Yesterday I had a flight from San Jose to LA. I didn't really
| plan for Ramadan when I booked the flight. I was scheduled to
| land at LAX at 6.45pm, about 25 minutes before iftar LA time.
| The plan was to land, have something light at the terminal
| then drive 1 hour back to my place.
|
| Well the flight got delayed about 25 minutes. It was going to
| land about 10 minutes after sunset. I was debating whether to
| buy something to eat before boarding. But then I can't have
| the tray open and eat when the plane is landing. I ended up
| breaking fast in the LAX terminal but around 30 minutes after
| I originally planned to.
|
| Its really nice flying during sunset though, the pink sky
| around LA was gorgeous.
| walrus01 wrote:
| Depending on the specific school of fiqh that the commenter
| follows, he could have also been totally fine not fasting
| at all if traveling more than 80 km beyond his home.
|
| https://www.google.com/search?client=firefox-
| b-e&channel=ent...
| esalman wrote:
| That's right! People who are used to fasting don't want
| to miss out regardless. I mean you get the best type of
| food in Ramadan which for some reason people don't make
| the rest of the year.
| yonatan8070 wrote:
| As an Israeli, on Friday and Saturday the train/bus schedule
| changes based on the time Sabbath starts (which is, iirc,
| when 3 stars are visible in the sky), meaning that in winter
| there's like one or two trains really late (like 22:00-23:00)
| on Saturday, and in summer there's like four or five,
| starting at a more reasonable time than 23:00.
| widforss wrote:
| I don't understand. The stars come out earlier in winter,
| but the train starts later? And wouldn't the trains rather
| stop when the Sabbath starts?
| yonatan8070 wrote:
| Sorry I got the words mixed up, wrote this too early
| lol..
|
| Sabbath starts on Friday, so trains end in the
| noon/afternoon, and start after Sabbath ends on Saturday
| evening/night.
| pm3003 wrote:
| Living among Muslim and Catholic people in a time of
| simultaneous Lent and Ramadan, I first read "How the Fast Days
| are getting longer" and thought "How true, how true".
| BLKNSLVR wrote:
| As a middle-aged human I first read "How the Fast Days are
| getting longer" as some kind of ironic commentary with the
| actual meaning being "how fast the days are getting shorter".
| user_7832 wrote:
| As a younger human I too clicked here thinking it was
| social commentary on the passage of time.
| Delk wrote:
| My initial assumption before clicking was that it was
| about the Earth's slowing rotation, and my thought was
| "not very".
| rzzzt wrote:
| If you would like to read some "time moves quicker"
| articles:
|
| "Why time 'speeds up' as we get older"
|
| - https://sites.harvard.edu/sitn/2019/03/27/no-not-just-
| time-s...
|
| - https://news.ycombinator.com/item?id=29109066
|
| "Why time seems to pass faster as we age"
|
| - https://news.ycombinator.com/item?id=39522249
| xvokcarts wrote:
| I think it speeds up because we settle in a routine, and
| when every day is mostly the same the brain just
| compresses the experience. The younger you are, the more
| new everything is around you, and you may not know yet
| what is worth trying or not, hence more things happen,
| and that makes it appear to last longer.
| andyjohnson0 wrote:
| _" The days are long but the decades are short"_
| walrus01 wrote:
| An interesting thing that non-muslims may not consider is that
| because Ramadan goes backwards in the western calendar approx.
| 10 days per year, for many people it'll be only a few times in
| their total lifespan when they experience and remember it being
| in the middle of summer and also in the middle of winter.
| esalman wrote:
| This. I was a high schooler when I had winter Ramadan. Next
| time that happens in 2031 I'll be 46, and 62 in 2047 when
| it's in the middle of summer. If I'm lucky I might get one
| more winter Ramadan in 2063 or something, _InshaAllah_
| crossroadsguy wrote:
| I am heading to the local cafe right now. This is the only time
| of the year they make Special Ramadan Phirni and they don't
| even share that exact recipe. I have begged them many times:
| either make it year round or for just give me the bloody
| recipe.
| esalman wrote:
| In Bangladesh we also make a bunch of different dishes only
| in Ramadan. I mean they are made all year round in
| restaurants, but in Ramadan every Muslim household and street
| corner vendors will make them- haleem (lentil soup with
| meat), piyaju/beguni (deep fried snacks made of onions,
| lentils and eggplant etc.), bundia/jalebi (desserts), sola-
| muri (chickpea dish with puffed rice), "rooh afza" beverage
| to name a few. Even my non-muslim friends would crave some of
| these dishes and look forward to Ramadan to enjoy these.
| MarceliusK wrote:
| It's fascinating how religious practices, like fasting from
| dawn to sunset, can make astronomical events feel so much more
| immediate and personal
| doctoboggan wrote:
| I've been using my iPhone in standby mode at night and I have the
| world map with the daylight "sine wave" on. Its been fun watching
| the shape of the daylight region change as it get closer and
| closer to the top of the map. After the equinox it pops through
| the top of the map and then it's upside-down for the next 6
| months.
|
| Watching the changing shape of the daylight illuminated portion
| of the map over the year has given me a much better understanding
| of what the equinox means, why daylight hours shift, and just in
| general a better appreciation of our place in the solar system.
| saevarom wrote:
| I'm from Iceland, so a latitude of about 64.15 or so. The
| extremities of the graphs kind of describe how the mood of the
| people swings up and down all year round. In the middle of
| summer, around the summer solstice, people are bordering on
| mania, enjoying endless daylight and trying to get the most out
| of each day. As winter solstice approaches, everything becomes
| more subdued, a bit depressed even. It's often a bit difficult to
| live with, especially during the shortest winter days, but the
| summers are so incredibly amazing that it feels like it's all
| worth it.
| coolThingsFirst wrote:
| Use the derivative, Luke
| ggm wrote:
| Do the maths for the southern hemisphere and compare: It is my
| belief due to axial tilt AND the solar rotation period and solar
| distance, the effects aren't entirely equal north and south pole.
|
| Do the maths for the dusk side of the story. Dawn is good, but
| how this behaves in the rate of sun appearance and rate of sun
| disappearance also has a shift, the two event peaks aren't
| aligned. Again, a function (I believe) of the axial tilt.
|
| So its a system with differences, with multiple inputs, with
| complex maths. I love it!
| bloppe wrote:
| It would be different in the southern hemisphere, but mainly
| due to the eccentricity of the Earth's orbit.
| balderdash wrote:
| I find the more frustrating / noticeable the equation of time for
| a given point, where solar time and local time diverge, day to
| day it feels very counterintuitive, but when you see the chart it
| makes complete sense...
| walrus01 wrote:
| Another way to visualize this would be to look at the DOE NREL
| solar intensity maps for mid-winter vs. mid summer:
|
| https://www.nrel.gov/gis/solar-resource-maps
| iam-TJ wrote:
| I have a wake-alarm[0] that triggers 30 minutes before civil
| twilight, that is roughly 60 minutes before local sunrise.
|
| In the northern hemisphere at 52 degrees it gets earlier by about
| 2 minutes each day (additional 4 minutes of daytime).
|
| So I get more sleep and short days in winter and less sleep and
| longer days in summer. It's liberating basing schedule on it and
| not some arbitrary time.
|
| [0]
| https://f-droid.org/packages/com.forrestguice.suntimeswidget...
| harywilke wrote:
| The author, Joe antognini, also has an excellent podcast on the
| history of astronomy called: The Song of Urania
| jazzcomputer wrote:
| I love this - shout out from the Southern Hemisphere though -
| would love to see our version of it.
| slyall wrote:
| The author has a great podcast on the History of Astronomy
|
| The Song on Urania https://songofurania.com/
|
| It's taking a break for 2025 but there are enough episodes there
| to give you enough to listen to until he restarts
| hi_hi wrote:
| Can someone do a similar analysis which explains clearly why I
| can see the moon during the day sometimes.
|
| I kinda understand intuitively, as the sun and moon obviously
| have different orbits, but I'd love to see actual visualisations
| of this, perhaps in 3D.
| hoherd wrote:
| Here is a physical 3D visualization (a LEGO set) showing the
| sun and moon orbits. My children and I put this together last
| year before the eclipse as a way for them to better understand
| why the eclipse was happening
|
| https://www.lego.com/en-us/product/planet-earth-and-moon-in-...
|
| In the set, the earth spins on its axis, the moon orbits the
| earth, and the earth orbits the sun. There are stickers that
| mark the months of the year so you can see when solstices and
| equinoxes happen.
| hi_hi wrote:
| I love this, thanks for sharing.
| lutusp wrote:
| An interesting analysis, covers a lot of ground, but no mention
| of the "analemma" (https://en.wikipedia.org/wiki/Analemma), an
| annual figure-eight curve that results from earth's elliptical
| orbit around the sun, and that must be included for reliable
| calculation of solar position and rise-set times.
|
| Calculating the analemma requires multi-term Fourier analysis to
| reliably pin down the sun's position, without which nautical
| sextant calculations would fail. Even in the GPS era,
| professional sailors are required to (demonstrate their ability
| to) turn sextant sightings into geographical positions, against
| the possibility of a high-tech failure.
|
| Apropos, during my around-the-world solo sail
| (https://arachnoid.com/sailbook), because of just such an
| equipment failure, I was obliged to navigate from French
| Polynesia to Fiji using a sextant -- and reliable solar
| positions.
| franze wrote:
| During a long hard winter night while I was longing for sun but
| the only warmth 1 got was from my screens, I coded
|
| https://daylight.franzai.com/
|
| to give me data and hope.
| jve wrote:
| Oh, I learned from the graphs that today, March 20, seems to be
| peak at Additional minutes of daylight we get.
|
| And that everywhere on the planet there is even split between
| day/night 12h/12h
| MarceliusK wrote:
| I knew days lengthened quicker around springtime, but your
| interactive visualization and clear breakdown of the math behind
| it makes this phenomenon tangible
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