When a liquid boils, the temperature has been raised to such a pitch that the evaporating molecules are sufficient in number and speed to lift off the air from the surface of the liquid and push it back en masse.

Broadly speaking, the discovery of X-rays has increased the keenness of our vision ten thousand times, and we can now 'see' the individual atoms and molecules.

The difference between surface and upper-air trends in no way invalidates the conclusion that the Earth's temperature is rising,

The difference between surface and upper-air trends in no way invalidates the conclusion that the Earth's temperature is rising.

When air is hot, the molecules move fast and they have high kinetic energy. The colder the molecules are, the smaller their velocities are and, subsequently, their energy. Temperature is simply a way to characterize the energy of a system.

At higher altitudes, there isn't enough air for ionized molecules to combine and become neutral again, so the region stays ionized. That's what the ionosphere is.