Didn't you say it was hot and cold? So why do you feel cold standing on the mountain?

Uh-oh, your question is very complicated. First of all, you have to understand why the place where we live produces temperature. The sun is the source of all energy, but the radiation emitted by the sun is short wave, and the atmosphere can only absorb long wave radiation. When the sun shines on the ground, the earth absorbs the long-wave radiation of the sun and radiates infrared rays with longer wavelengths, resulting in a temperature suitable for our survival. So the closer to the heat source, that is, the ground, the higher the temperature. As for the rise of heat and the fall of cold, it is also correct. Only in this way can we produce weather like wind and rain, which is why the lowest atmosphere is called the troposphere (the troposphere on the first floor is called the stratosphere, which is characterized by cooling and heating, and the heat source is the ozone layer, so don't mislead others).

As for the hot air balloon, firstly, its temperature is much higher than the surrounding air; The second is to replenish calories at any time. Let me give you an example. Boil water. Before the water boiled, although the hot water rose and the cold water fell, the bottom of the pot was still hot, wasn't it?