Bill nye says our change in seasons is largely due to the fact that the directness of the sunlight hitting a given place changes due to the earths tilt and position in its orbit.
Why does the directness of light create more heat (hitting at equator for example), while glancing light rays (hitting antarctica) produce less heat?
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They don’t. It is that glancing light is more spread out, so while the amount of heat is the same it is spread over a larger surface. If the surface is facing directly towards the sun, it will appear to be wider from the sun’s perspective, and so it will gather more sunlight despite not actually being any bigger. This makes it gather more heat, too.
Here’s an experiment you can actually do that can help you visualize it better. Get a lamp and a sheet of paper. Shine the lamp onto a wall with the paper between them and look at its shadow. You’ll notice that the shadow of the paper is larger when it’s face-on than when it’s at an angle. This allows you to see with your own eyes that there’s less light shining on the paper and instead getting to the wall when it’s at an angle.
Shine a torch straight down on the floor in a dark room. It makes a perfect circle with the light, and heat, all concentrated within that circle.
Now tilt the torch so that the light hits the floor at an angle. Your circle turns into an eclipse or egg shape. The same amount of light and heat is more spread out so any point inside the eclipse is slightly cooler than the points inside the circle even though the same torch putting out the same energy produced both shapes of “light”.
The angle makes a difference.
The simplest way to put this is just that it’s the same amount of light spread out across a larger area.
Hold a flashlight 2 feet from the wall, and point it straight at the wall. Then, tilt the light to an angle. More of the wall is illuminated, but the light didn’t get any more powerful.
That’s because the light is now more spread out.
Another analogy: if you put your hand out the car windows when you are driving, you feel a stronger push from the wind when it is facing the wind. As you tilt it, you feel less pressure
This is called the projection effect, and can be demonstrated by shining a flashlight directly onto a surface, then tilting it. The same light gets spread over a much larger area. So you might have say 1 watt per 1 square centimeter vs 1 watt per 4 square centimeters. The light source didnt change intensity at any point, just the directness. (you should also keep the flashlight at basically equal distance from bulb to paper, the real difference in distance is trivial.)
Another major reason is the atmosphere and the fact that it absorbs/redirects radiation as well.
Light hitting Antarctica travels through much more atmosphere. Draw two circles, one just a bit bigger than the other. Starting at the edge of your paper, draw two lines (originating from the same spot), one to the closest point on the inner circle, and the other to the furthest edge you can reach in a straight line, and observe how far that line travels through the outer circle.
There are 2 reasons and most comments so far only focus on 1 reason: that the light hitting earth at an angle (near poles) is spread over a larger area (than when it would straight hit close to the equator), which is totally true
The 2nd reason though is that light travelling close to the equator has to travel less distance through the atmosphere than when it would when travelling to a pole
Sunlight coming at an angle has to travel through more atmosphere before it reaches the ground where it “loses” more energy on its way there. (Obviously energy is never lost)
Also obviously longer/shorter days have an impact on how much the surface can heat up/cool down.
There was a recent ELI5 where someone likened it to a torchlight beam being shined straight on (small circle) or at an angle (large oval). Same total amount of energy spread out across a much larger area, therefore each point must be getting less energy.
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