I don't know off hand what this cliche wave is called(shown in like all SciFi space launch movies) the wider top part of the wave that's the Earth tilted in that direction? eg. northern part is exposed towards the sun more. At this time for me in US.
As cosmic_quanta mentioned it's called the terminator, and it's generally the dividing line between the 'illuminated' and 'unilluminated' part of a celestial body.
You're right, the weird shape is due to the projection of "earth" in the X-Y plane, if you chose a different projection it would appear differently. The calculations make sure that the result is ±1 accurate all year long.
The truth is that even the definition of 'daylight' and 'night-time' is not straightforward. The most common definitions include the Civil, Nautical and Astronomical Twilights [1], depending on the sun's position, so it should actually be a gradient.
Huh, I wanted to draw something exactly like this to put as hero image of my company page, except with ISS orbit instead of the terminator. I really like this "world map out of dots" style.
Thanks! I was inspired by the world map that appears on my android's Clock application, and it was an opportunity to write some structured matplotlib code and learn about new stuff.
You might want to take a look at the Natural Earth [1] datasets and GeoPandas [2], they're great if you're dealing with any kind of geographical data.
Out of interest - how are you getting location? I didn't get a consent warning for client side geolocation and it seems accurate so it doesn't appear to be IP based (my public IP appears to be a few hundred miles south of my actual location).
I've gone back and forth on replacing this with a browser-based location request so the user is aware what's going on -- the tradeoff being the friction of clicking the allow button.
You'll find this sort of visualization on a lot of ham radio websites, since skywave propagation between two points varies based on the amount of sunlight among other things. For instance, https://www.pskreporter.info/pskmap.html
"Because the lower-altitude layers (the E-layer in particular) of the ionosphere largely disappear at night, the refractive layer of the ionosphere is much higher above the surface of the Earth at night. This leads to an increase in the "skip" or "hop" distance of the skywave at night."
It's not quite as simple as that, because there are multiple ionospheric layers with different physical properties that affect RF propagation.
An over-simplified explanation is that the outer layers of the atmosphere persist continuously, and can be used for very long distance communication, but only reflect radio waves at relatively low frequencies (<10MHz). The lower layers that become ionized during the day absorb some of the radio waves, reducing overall efficiency and range, but also allow operation at higher frequencies which would be unusable at night.
It's complicated. There are various "layers" of the ionosphere that "bounce back" radio waves in different bands of frequencies depending on the time of day. It's a fun topic to learn about.
Modifying the Python code for this would be trivial. I need to think about how to best serve each 'session' though, or transfer the image generation to the client-side. Nice plan for a weekend!
Can't you use a static image on the server and compute the terminator on the client side? That way it would always be up-to-date even without a reload.
Interesting that these maps are always binary: light or dark, when the intensity of light varies based on how high the sun is in the sky. Is there a version of this map that takes that into account?
As a start, it will be nice to just show the relative intensity of the light ignoring clouds and stuffs ... for example, people should know early morning, mid day and evening from the map which helps which part of the globe is going to get active/inactive
I'm thinking more of an Irradiance map where the value is the current W/m^2 at a specific location, which would take into account latitude and time of year (to get the angle of the Earth relative to the sun), along with other factors like clouds, altitude.
Human vision has two logarithmic-response mechanisms in a row: the expanding/contracting iris, and the rods/cones (and many other nerve cells') logarithmic response.
Meaning: you get full visual acuity with just a little light. Further increases often don't even register.
In numbers: typical overcast daylight is around 1,000 lux. Full sunlight is above 100,000 lux.
This is a really useful visual if one has contacts or meetings in other world cities. The left edge of the light hump is roughly 6am, the center is noon, and the right edge is roughly 6pm. The center of the dark hump is midnight, give or take DST.
It's one of the main reasons I still use Mate. No other desktop environment keeps it handy like this. I try them for a bit, then always go back to Mate.
Offtopic but MATE is also literally the only Linux desktop that gets multi-head right, especially when it comes to hot-adding and hot-removing displays. All others do weird things to the window layout or crash when you add or remove a monitor while the machine was asleep.
It is another cool feature I didn't think about, thanks!
To arrange meetings and sync with remote teams, I'm looking up timetables on a small Go utility.[1]. You can check it in action in the Go Playground [2].
I'd love to use this as a clock pane in my window manager. If you added the local time and removed some of the large text, it would be a great background.
This reminded me of a moving city on Mercury called Terminator from Kim Stanley Robinson‘s novel 2312. The city slides along metal tracks propelled by the expansion and contraction of the metal as the terminator of the sunlight shifts. There’s even a sun cult that chases perpetual dawn. It’s a pretty good science novel.
You can actually just link the image to your desktop and depending on settings will auto update throughout the day. Sometimes you need to write a script
You can get a live map of where the sun is shining from Google maps. Just switch to satellite view and zoom out until you see the whole earth, then a bit more.
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[ 6.3 ms ] story [ 65.4 ms ] threadhttps://en.m.wikipedia.org/wiki/Terminator_(solar)
You're right, the weird shape is due to the projection of "earth" in the X-Y plane, if you chose a different projection it would appear differently. The calculations make sure that the result is ±1 accurate all year long.
The truth is that even the definition of 'daylight' and 'night-time' is not straightforward. The most common definitions include the Civil, Nautical and Astronomical Twilights [1], depending on the sun's position, so it should actually be a gradient.
[1] https://en.wikipedia.org/wiki/Twilight
Huh, I wanted to draw something exactly like this to put as hero image of my company page, except with ISS orbit instead of the terminator. I really like this "world map out of dots" style.
You might want to take a look at the Natural Earth [1] datasets and GeoPandas [2], they're great if you're dealing with any kind of geographical data.
[1] https://www.naturalearthdata.com/
[2] http://geopandas.org/
https://epic.gsfc.nasa.gov/
Can't find it any more though - probably been removed.
Would love to figure out how to incorporate a world dot map like this, but showing the two current golden hours (morning and evening) instead.
[1] https://github.com/ksho/whenisgoldenhour.com/
https://github.com/ksho/whenisgoldenhour.com/blob/master/pag...
I've gone back and forth on replacing this with a browser-based location request so the user is aware what's going on -- the tradeoff being the friction of clicking the allow button.
My location resolved a province over, so I suspect it is at least somewhat IP-based (or IP + some other magic)
[0] https://github.com/ksho/whenisgoldenhour.com/blob/3c0d7f0acf...
The Geochron (https://www.geochron.com/about/what-is-it/) is a mechanical map+clock created in 1965 that shows it.
https://en.wikipedia.org/wiki/Skywave#Other_considerations
An over-simplified explanation is that the outer layers of the atmosphere persist continuously, and can be used for very long distance communication, but only reflect radio waves at relatively low frequencies (<10MHz). The lower layers that become ionized during the day absorb some of the radio waves, reducing overall efficiency and range, but also allow operation at higher frequencies which would be unusable at night.
And you can get very efficient long-distance propagation along the terminator at dawn and dusk: https://www.qsl.net/w2vtm/grayline.html
e.g. https://www.nrel.gov/gis/images/solar/solar_ghi_2018_usa_sca... but on the daily.
The page could be modified to present a gradient, since it only requires calculating the sun's altitude and solar time, which is not that complicated.
[1] https://en.wikipedia.org/wiki/Twilight
Meaning: you get full visual acuity with just a little light. Further increases often don't even register.
In numbers: typical overcast daylight is around 1,000 lux. Full sunlight is above 100,000 lux.
Gnome2 had a map like this in its calendar/time drop-down when you add cities to it: https://help.gnome.org/misc/release-notes/2.22/figures/rnuse...
It's one of the main reasons I still use Mate. No other desktop environment keeps it handy like this. I try them for a bit, then always go back to Mate.
To arrange meetings and sync with remote teams, I'm looking up timetables on a small Go utility.[1]. You can check it in action in the Go Playground [2].
[1] https://github.com/tpaschalis/Golang-practice/blob/master/ti...
[2] https://play.golang.org/p/vYSmZ3oeOLE
http://www.fourmilab.ch/xsunclock/
Want another challenge? Try one with the azimuthal equidistant projection. Would be quite interesting to watch the comparison.
https://www.die.net/earth/
You can actually just link the image to your desktop and depending on settings will auto update throughout the day. Sometimes you need to write a script