*Some people say they don’t see the gulf radar returns on certain apps.
*I may have jumped the gun on this one about the 58k’ cloud. Though unusual for a non tropical storm, cloud tops can get that high or higher for extremely strong convective storms.
Clouds are water vapour, how cold is it at 58,000ft?
Surely that’s insta-snow?
Low altitude clouds are a mixture of water vapor and water droplets. High altitude clouds are a mixture of water vapor and ice crystals. The rain generation process involves the accumulation of droplets that are cycled from low to higher altitudes where they freeze into hail and then melt on the down cycle. When they fail to melt, we get hail. The air temperature at 58,000 feet is about -55 C, far below freezing.
Thanks pal. That’s some cold air, what would stop the cloud turning to ice and falling as one big huge lump of ice?
They are ice, but in crystals. If particles are small enough, they become aerosols and viscous forces become more important in their movement than buoyancy. Also, the water vapor in which they are suspended is lighter than air, so the cloud mass has neutral buoyancy. When the crystals accumulate or grow, they become snow and precipitate (but mostly at lower altitudes).
I used to wonder at the question of how clouds could be water droplets, yet be aloft. Until I realized that the droplets are in equilibrium with their own vapor, and water vapor has a molecular weight of 18 and air has a molecular weight slightly higher than 28, so the water vapor was providing buoyancy.
It’s crazy until you realise air is a liquid.
Thanks KSR.