For a successful photo shoot, usually requires serious preparation. And if you were going to shoot a sunset, it would be nice to know in advance how beautiful this sunset would be.
The concept of beauty, of course, is individual, but still there are some moments that determine the beauty of the sunset, some elements of beauty, about which most people will agree.
Sunset elements
1. The sky in the place where the sun sets over the horizon.
If the sky in this place is clear - it is beautiful.
If there is a clear strip of sky, and above it clouds are even more beautiful.
If there is little cloud and the sun sets in the middle of the clouds - also not bad.
If the whole sky near the horizon in the clouds is bad.
Examples:
The sun sets without clouds on the horizon
Cloudy on the horizon
Cloudy on the horizon
Near the horizon - a clean strip, closer - solid clouds
2. Clouds above us and west of us after sunset
Sometimes, right after sunset, the clouds are illuminated by the setting sun. And the more time has passed since sunset, the more red and beautiful the color of these clouds.
We are looking towards the Sun, to the West, therefore we are interested in the clouds by us, to the north and south of us, but the clouds to the west of us are especially interesting.
We need 1) They were 2) As much time as possible after sunset was lit.
Actually, this is dawn, but the idea is the same - a continuous layer of clouds illuminated by the Sun which is still (in the case of sunset - already) not visible
This is sunset, low clouds lit by the setting sun
Low clouds - in the shade, high - lighted
Partly cloudy, but the clouds are tall and lit by the setting sun.
Clouds still illuminated after sunset
3. Sky color
Sometimes it happens that the color of the sky after sunset is saturated, bloody, red.
And sometimes faded, orange.
Red sky at sunset
Red sky after sunset
Model for getting sunset elements.
1. Clouds at sunset
Where are the clouds that are visible near the horizon? This, of course, depends on 1) the height from which we look 2) the height of the clouds 3) From what is in the west and where we generally have the horizon.
Assuming that the sea is in the west (after all, I live in Israel), and that we are standing on the shore, we get the picture:
It turned out that the angle A + B is equal to arccos (R / h + R) + arccos (R / H + R)
And one degree corresponds to 111 km
If we take a shooting height of 1.5 meters, then for clouds of different heights we get a plate:
Cloud Height | Distance 2000m | 160 km 5000m | 250 km 8000m | 315 km
We are still interested in clouds just above the place of sunset, for them we take the distance from the lantern is half that of the distance to the clouds on the horizon.
2. Lighted clouds after sunset
I came up with this calculation
This shows the extreme position of the Sun, at which it still illuminates the clouds above me
Let's make a tablet again
Cloud Height | The time after which the Sun will cease to illuminate | The distance to the clouds on the other side of the horizon 2000m | 5.5 min | 310 km 5000m | 8.8 min | 490 km 8000m | 11.1 min | 619 km
Here, of course, there is an assumption, completely unfounded, that the clouds on the other side of the horizon are at the same height as the clouds above me.
Given the uncertainty with the height of the clouds, I just check if there are clouds in the direction of the Sun 5 and 10 minutes after sunset and at a distance of 300 and 500 km, respectively.
If both here and there are clean, you can hope that the clouds will be lit after sunset
3. About the color of the sky, I found two articles, but have not yet figured out how to implement these ideas
It says that if in the west the pressure is high, then there is stable air and dust particles remain in the air and there will be more refraction.
But there is no information about how high the pressure should be in the article.
Can it just look if there is a wind? And at what point? Unclear.
And here it is described in more detail about the types of particles in the atmosphere. It is necessary to read and understand, but in any case, this information is not particularly taken
Where to get data
I started with the dark sky site API.
However, there was no data on the height of the clouds. In this and other international sites there is information only about the percentage of cloud cover.
Soon a second problem was discovered - the low accuracy of these global forecasts. Here in this article the difference between local and global models is well described and why global models do not give high accuracy.
The height of the clouds and a more accurate forecast I tried to get from the TAF API . These are aviation forecasts. They are accurate, with the height of the clouds, but the data is only for aerodromes. Those. in my case, I only got a forecast for Ben Gurion Airport.
As a result, I contacted people from the Israeli meteorological center and it turned out that there is an official way (although not advertised) to receive their forecasts, which are calculated twice a day based on the local model.
These forecasts come as GRIB files, for which there are many parsing libraries.
The accuracy has seriously improved, but now I can only predict sunsets in Israel :)
To calculate the sunset time and I use the library www.time4j.net
And for geometrical calculations with earth coordinates github.com/grumlimited/geocalc
All the photos in the article are mine.
They and others can be found on my website.
Happy hunting photo!
PS I'm not sure what I placed in the correct hubs, if you need to transfer it, tell me where.