I can explain a couple of those.
1. Air pressure... Gravity holds the air from flying off into space. If it didn’t, we wouldn’t have any air to breathe. The air pressure on earth is about 15 pounds per square inch. This means that every square inch of earth has about 15 pounds of air above it, if you totaled the weight of the air molecules all the way out until there aren’t any more. The higher you go, the less air there is above you to create that pressure. When you pressurize air it gets hot. All the energy it takes to make the pressure is turned to heat in the air. When you release that pressure, it cools by the came amount. That’s why air compressors need cooling fins. That means, the higher you go the colder it gets since the pressure is lower. It’s called the “lapse rate”. Look that up if you want more information about this.
2....Meteors and spacecraft get hot only because they’re coming in at an extremely high speed, thousands of miles per hour. When they hit molecules of air, they accelerate that molecule to nearly the speed they are travelling. Much of he energy of the collision (mass times velocity squared) in that molecule is turned into heat in the impacted item. At the very low speeds of cooling fans, the energy of the collision is negligible, and much of the cooling effect is either evaporation of sweat on a person’s skin, or also the cooler temperature of the blowing air.
I hope that helps for these two.
2.
Thanks.