The mesosphere burns up most meteors and asteroids before they are able to reach the earth's surface.The mesosphere is the coldest atmospheric layer surrounding the earth. It becomes cold enough to freeze water vapor in its atmosphere into ice clouds.
The main reason why Earth is warmer at the equator than at the North and South Poles are thats where the sunlight shines at a lot of times. The sunlight never really shines directly at the North and South Poles like it does with the equator.
