Why is it so cold up in the air at three km over the earth although the sun is shining?

Question

The sun is so hot. When there are no clouds in the summer, it is so hot. But when you fly at 3000 meters, it is so cold, about minus 50. Why is it so?

Answer 1

the greenhouse gases that keep the earth warm don't carry out on those altitudes.

Answer 2

This effect is all about the atmosphere. Here on the surface of the planet, the relatively dense layer of gases traps heat from the sun. The farther out you go, the less dense the atmosphere becomes, and the colder it gets.

Answer 3

The rays of the sun stike the earth and the energy is converted to heat. the farther you get from this heat source the ccolder it gets. As you go up in altitude the air temperature drops about 3 to 4 degrees per thousand feet.

the -59 you mention at 3000m is unrealistic for that altitude unless you are talking about AGL (Above Ground Level) and you live on a mountain top in Alaska and it's January.