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.
"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"
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.
https://www.google.com/search?client=firefox-b-e&channel=ent...
Sabbath starts on Friday, so trains end in the noon/afternoon, and start after Sabbath ends on Saturday evening/night.
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.
https://www.usccb.org/prayer-and-worship/liturgy-of-the-hour...
Rome today: https://wdtprs.com/2024/04/rome-24-3-day-13-14-easter-tuesda...
Any public liturgy around here is fixed to civil time so that normal laypeople can join.
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.
Is it now?
I mean, yes the sighting of the Sun is a solar-related reckoning of time, but the solar calendar is based on the Earth's orbit around our Sun and the way that orbit changes the Earth's relative axial tilt in relation to the part which faces Sunward, yes?
On the other hand, a sunrise and sunset are not so much dependent on our orbit at all, but your particular latitude and longitude at any given point in time. Sunrise and sunset, in terms of orbital mechanics, aren't dependent on Earth's position in space or its orbit, but on the observer's position on Earth: where either the terrain/shadow obscures the Sun from our view or it doesn't. You can easily modify the phenomena of sunrise or sunset by traveling elsewhere, regardless of the solar calendar's season or our axial tilt.
Our solar and lunar calendars are reckoned by solar and lunar activity, and Earthbound Leadership adjusts those calendars so that they're calibrated to that activity. On the contrary, with our civil time fixed in an abstract 24-hour cycle and sliced up into 60-minute time zones (give or take), sidereal time is sort of divorced from clock time, and we rarely attempt, in modern times, to calibrate civil time according to the Sun's actual meridians at all -- but we do, in fact, find it necessary to compensate for variations in the Earth's rotation.
Ask any astronaut about sunrise and sunset, because for a satellite orbiting Earth, the Moon, or a probe which is traveling somewhere, those are alien or malleable constructs.
The Arabic Islamic calendar is not like that. Ramadan is one of the standard months of the lunar calendar and depending on what year you're talking about, Ramadan might be exactly in the middle of summer, or it might be in the direct middle of winter. Very approximately it goes "backwards" in seasons 10 or 11 days per year and eventually wraps all the way around from the POV of the western solar calendar.
In the western calendar, the winter solstice will always fall on December 20th or 21st even going up to the year 2100. And the same for the summer solstice on June 20th or 21st.
Every calendar that I'm aware of considers "days" as an abstract unit which consists of one planetary rotation, without nuances of activity or visibility of external bodies, right? True?
You are right that the human perceived calendar date is something we invented rather arbitrarily. Of course, the longest day of the year was occurring on June 20th before humans invented agriculture or cities. That we call it "June" and "20" is a cultural artifact.
Check your geocentrism
The Sun’s relative, apparent position.
Sunrise and sunset are wholly dependent on the observer’s position because “night” is a cultural construct referring to being within the Earth’s shadow rather than a dragon devouring the Sun, yes?
How apropos and now I'm curious how many English speakers don’t really consider how a “mildly profane” adjective had its start as a blasphemous slur against the Eucharist and a certain Queen?
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.
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!
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!
I'm originally from São 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.
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.
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.
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.
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.
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.
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.
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.
Winter is… Sunrise at 08:12AM and Sunset by 04:00PM(16:00).
You can technically use this info to guesstimate my location ;)
> The whole "6am sunrise and 6pm sunset every day of the year" thing at the equator is kind of mind blowing.
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/climateAnother mind blowing thing about the equatorial sun is seeing it above you! Where I grew up, the sun is never higher that 30 degrees.
The silver lining is that our longest days are often our sunniest.
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.
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.
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.
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
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.
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.)
For me X is then a "travelling" value which in the winter is at 1/3 between sunset (0°) and civil dusk (-6°), 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.
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.
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.
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.
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 :)
nox -> noctes, so equinoctes, if you're feeling Latin
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.
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).
to give me data and hope.
It depends on the latitude for sure, but also I think on the time of the year?
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!
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...
How fast the days are getting long and so
The summer rains are melting all the snowThe 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.
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.
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!
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.
> 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?
You'll also be able to understand time zones and great circles (flight paths) better with a globe.
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".
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.
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
Is the graph correct at those extremes? Like North Pole?
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.
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)
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. :)
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.
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.
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.
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.
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 :(
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’.
The shortest day still has 7-8 hours of daylight. There's no shortage of daylight, we have too much work.
And that everywhere on the planet there is even split between day/night 12h/12h
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.
Then we “make days shorter “ resulting in a 25 hour day.
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.
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.
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.
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.
Unless you're inland, where it's ninety billion degrees in the shade half the year.
Nice place.
Temperature-wise, most of the UK is actually quite moderate compared to central Europe. It's winter darkness that gets to you.
Why? What help does it make adding one extra hour to the start of the day, when the day lasts like ~4 hours.
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.
https://www.bbc.com/future/article/20170314-the-town-that-bu...
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).
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.
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.
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.