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How fast the days are getting longer (2023)
- harywilke 2y agoThe author, Joe antognini, also has an excellent podcast on the history of astronomy called: The Song of Urania
- MarceliusK 2y agoI knew days lengthened quicker around springtime, but your interactive visualization and clear breakdown of the math behind it makes this phenomenon tangible
- porkloin 2y agoI 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 2y ago> equinoxes (equinoxii?) nox -> noctes, so equinoctes, if you're feeling Latin
- tcoff91 2y agoWhat makes you choose to live at such an extreme latitude? I'm always curious about what draws people to live in such places.
- porkloin 2y agoI 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 2y agoNice typography. Classy.
- lars512 2y agoWhen 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 2y agoSimilar experience for me but probably even more extreme. 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.
- Zanfa 2y agoHaving 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 2y agoCatches 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 2y agoYou 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.
- deleted 2y ago[deleted]
- madcaptenor 2y ago"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 2y agoNot 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 https://www.timeanddate.com/sun/norway/longyearbyen
- alberth 2y agoThe graph gets crazy if you move the slider to be 66+ latitude. Is the graph correct at those extremes? Like North Pole?
- returningfory2 2y agoYes. 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 2y agoThe 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 2y agoI'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 2y agoIt'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 https://brr.fyi/posts/sunset) and a sunrise (https://brr.fyi/posts/redeployment-part-one https://brr.fyi/posts/redeployment-part-one)
- aeyes 2y agoUnfortunate that the latitude is not allowed to be negative.
- kaffekaka 2y agoComing 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 2y agoI 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 2y agoI always think of what time is sunrise where I am. Watching it get earlier/later every day by a couple minutes.
- bitmasher9 2y agoThis 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 2y agoThe 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.
- munchler 2y agoThis 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 2y agoThe 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 2y agoI think the section “Atmospheric refraction and the solar limb” near the end of the article addresses this.
- madcaptenor 2y agoNot 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 2y agoYeah, you’re right. Something like civil twilight, as you mentioned above, should get it closer to what is being discussed here.
- madcaptenor 2y agoThat'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 2y ago
- 1ewish 2y agoWhat 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 2y agoIn 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 2y agoPontianak 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 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 2y agoIt'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.
- NorwegianDude 2y agoIt'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 2y agoI'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 2y agoI 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 2y agoI 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 2y agoSeattle says hi.
- MarcelOlsz 2y agoI was under the impression that Seattle was ultra sunny.
- kccqzy 2y agoVery 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 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.
- keepamovin 2y agoNice iambic pentameter in that title. How fast the days are getting long and so The summer rains are melting all the snow
- mig39 2y agoMoving 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 2y agoScotland then :-)
- yu3zhou4 2y agoThanks for posting! It's a good read, quite Bartosz Ciechanowski esque
- antognini 2y agoThank you! That's high praise! :)
- blackeyeblitzar 2y agoFor the Americans, daylight savings time also changes the perception of how the days are getting longer.
- dkdbejwi383 2y agoDST exists in a lot of the rest of the world too
- frankus 2y agoThe 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 2y agoFunny 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 2y agoWhat 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 ;)
- henrikschroder 2y agoI 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.
- LeoPanthera 2y agoDST 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 2y agoYou 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 2y agoYeah 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 2y agoDST 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 2y agoDST 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 2y agoI 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 2y agoShortest 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 2y agoI’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’.
- divbzero 2y agoA closely related follow-up blog post could be titled: “How Long Twilight Lasts”.
- tasuki 2y agoI'd love to read that! It depends on the latitude for sure, but also I think on the time of the year?
- madcaptenor 2y agoPlay 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 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 2y agoAh 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 2y agoI think you're right about the angles but I can't picture it well enough to understand why.
- antognini 2y agoYou'd be able to do it based on the math in the article. Civil twilight lasts from sunset until the Sun is 6° below the horizon. So in the spherical law of cosines in the article, you'd just set a to be -6° instead of 0.
- appleorchard46 2y ago(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 2y agoJuly 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.
- frogulis 2y agoWhat'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 2y agoThe 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.
- jader201 2y agoSomething 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 2y agoThere 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 https://en.wikipedia.org/wiki/Rule_of_twelfths, the diagram explains it better of course
- madcaptenor 2y agoRestated in mathier language: sin(30 degrees) = 1/2 and sin(60 degrees) isn't that far from 5/6.
- widforss 2y agoThat was a fascinatingly good approximation of sin().
- soloFU 2y agoAll 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 2y agoFasting 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 2y agoThe 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 2y agoSo 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 2y agoMy routine changes depending on location and the year anyway.
- travisjungroth 2y agoSolar calendar user, meet lunar calendar user.
- thaumasiotes 2y agoI'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.
- doctoboggan 2y agoI'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 2y agoI'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 2y agoUse the derivative, Luke
- ggm 2y agoDo 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 2y agoIt would be different in the southern hemisphere, but mainly due to the eccentricity of the Earth's orbit.
- deleted 2y ago[deleted]
- balderdash 2y agoI 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 2y agoAnother 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 https://www.nrel.gov/gis/solar-resource-maps
- iam-TJ 2y agoI 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/ https://f-droid.org/packages/com.forrestguice.suntimeswidget...
- jazzcomputer 2y agoI love this - shout out from the Southern Hemisphere though - would love to see our version of it.
- cytocync 2y ago[dead]
- slyall 2y agoThe author has a great podcast on the History of Astronomy The Song on Urania https://songofurania.com/ 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 2y agoCan 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 2y agoHere 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-orbit-42179 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 2y agoI love this, thanks for sharing.
- lutusp 2y agoAn interesting analysis, covers a lot of ground, but no mention of the "analemma" (https://en.wikipedia.org/wiki/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 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 2y agoDuring 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/ https://daylight.franzai.com/ to give me data and hope.
- jve 2y agoOh, 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