I asked this in school and the teacher thought I was trolling and didn’t answer me. It’s been like 20 years and I still think about it, it drives me crazy lol.
In: Planetary Science
As others have said, cold is not a thing. Cold is just less hot and anything warmer than absolute zero will have molecules that move. So look at absolute temperature in Kelvin. The lowest recorded temperature on earth is -89.2°C = 183.95 Kelvin. Highest temperature is 56.7C = 329.85 K. Earth average temperature is about 15C =288K
So there are no cold winds just more or less warm winds. We can heat up air cooler than our bodies, so a cold wind could just be one that can reduce out temperature. Our body core temperature is about 37C =310K, quite a lot over absolute zero.
You can calculate the average speed of particles in the air, that is the [https://en.wikipedia.org/wiki/Thermal_velocity](https://en.wikipedia.org/wiki/Thermal_velocity) For air at 20C it is 464m/s, the speed of sound at the same temperature at sea level is 343m/s.
464/343= 1.35 This means the average speed of molecules in air is Mach 1.35
(1.35 times the speed of sound)
You can compare that to a category 5 hurricane that requires sustained wind speed above 70m/s. A storm on the Beaufort scale is 24.5–28.4 m/s. the higher measure wind speed was 113m/s in a guse in a tropical cyclone. So the wind speed you are used to is tiny compared to the speed at which the particles ait move because of the temperature.
The wind is not the average speed of the molecules increase, it is that the direction in which molecules move is not random but slightly more in one direction.
We do not experience this motion of air as a win, what we experience is as pressure because molecules hit us evenly from all directions. According to Bernoulli’s Principle if there is a net motion of a fluid the pressure drops. Wind do this you can show it for yourself by blowing air and having two pieces of paper https://youtu.be/ORd2pgKbM6M?t=65
Compared to people walking all at the same speed in random directions in a large room, when something or someone is in the way they change direction randomly. There will be no net motion of people.
Compare that to the same people walking in at the same speed but all in the same direction you have the net motion of people. But the kinetic energy of the people is the same because their mass and speed are the same.
Wind is more like people prefer to walk in one direction but not just walk in that direction.
So-net motion do not require an increase in average speed, only a change in direction is required if there was motion to begin with.
This all means you can have a wind that moves a bit over the speed of sound without changing the average speed of molecules, That would mean the temperature has not changed. That is in theory, in practice that would not happen, all molecules will not move in the same direction. But it can and do happen at a lot lower air speed like the one we experience in wind on earth.
If have the wind at Mach 2, you likely get it from singing moving through the air like a jet fighter. The speed of the molecules in the air will indeed result in air that gets warmer from the point of view of the airplane.
Heat is a problem for supersonic airplanes. The airplane bodies get heated up and expand. An SR-71 that cruised at Mach 3.2 had a skin temperature of around 300C. It was made of metal that could handle that. There is one common way to get rid of heat for a supersonic airplane, use the fuel at cooland and heat it up with heat exchangers before you pump it into the engine and burn it.
During atmospheric reentry, spacecraft travel at a speed of around Mach 25. It compresses the air in front of it that heated up. It is the kinetic energy of the spacecraft that is transferred to heat in the air and that slows it down.
So how high wind speed is possible depends on temperature. It ic possible to have the wind at the speed of the temperature we have on Earth by just changing the average direction of motion of molecules. It is when you stare to move at speed greater then Mach 1 that you start to have significant heating of airplanes from wind.
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