A classmate feels that the weather is getting colder and darker every day recently. ...

The vernal equinox and the autumnal equinox are half of the sunshine time and equal to 24 hours, that is, the day time and the night time are equal.

Summer solstice has the longest sunshine time.

The sunshine time from winter solstice is the shortest.

Our country is generally in the northern hemisphere. As the rotation axis of the earth is inclined, as you can see, it is inclined from bottom to top to right. But the sun won't. It shines around.

Let me tell you first that A should be the summer solstice, B should be the autumnal equinox, C should be the winter solstice, and D should be the vernal equinox.

Because it's not in front of you, it's best to point the pen at the pen. Understand for yourself. Take a as an example. Have you ever found that at the top of the Arctic Circle, there is almost always light, while at the top of the Antarctic Circle, it is almost always dark? You can imagine blowing a hair dryer at yourself. If you don't move the hair dryer, in order to make the hair on your head dry faster, you will hook your head and tilt it slightly to let it touch the wind in a larger area. That's the truth. Look, location A, does it look like your head is facing the sun? C is running away with his head on his back. So there will be more shadows.

As for b and d, it doesn't matter if you tilt your neck in the positive wind direction.

Well, it seems unclear. I can only try my best to do this. I can't help it I'm just saying I can't draw it myself. I can't.

Perfect it again, because it is also related to rotation. You'd better take a small candle as a light source at home, then take a lollipop, learn to tilt the earth, rotate around the candle, tilt with your own axis and make a gesture, and you will find the problem. Draw a point on the lollipop as a checkpoint.

In that place from summer solstice, it will stay in the light for longer than in the dark.

One lap of lollipop counts as "one day".