90% of the atmosphere is within 10m km of the surface. The solar energy that is absorbed during the day is carried upwards by convection and radiated to space overnight. That's why you sleep under a doona or a pile of blankets. You can walk 6 km in an hour and a balloon rising at that rate would escape the influence of 90% of the mass of the atmosphere in less than two hours. In the first km and every km thereafter the temperature of the air will fall by about 9 degrees C. So, air temperature can be at freezing point at an elevation of just two kilometres. Air at freezing point has no warmth to warm the air below it or your body. There is no climate crisis, its an urban myth. A green nightmare.

The atmosphere is gaseous. A gas that warms becomes instantly lighter and is rapidly displaced upwards.

The temperature of the air depends on whether it is coming from a warm or cool place and how much energy that it can pick up from the surface of the solid or liquid surface along the way.