They happen in the night, and they happen in daytime. Why not in the morning? At least, why not so often?
In: Planetary Science
Those storms are driven largely by temperature gradient. During the day the ground warms up, warming up the air right over it, which is less dense and rises (convection). It’s this convection that ultimately drives the storm.
At night, without the sun to heat the ground, that convection slowly peters out and can even stop or reverse. It doesn’t stop immediately, because the ground builds up some heat over the day, and it takes awhile for it to go away.
So as the day goes on, the probability of a storm gets higher and higher due to the heating, then after sunset it subsides as the built up heat bleeds away, until morning, when the ground is coolest, and you have the lowest chance of a storm developing.
Thunderstorms require 3 ingredients: moisture, unstable air, and lifting action
Unstable air occurs when a parcel of air is warmer than the air above it, so it naturally wants to rise (hot air rises). How does lower level air become warmer than the air above it? The sun heats the earth’s surface, which then radiates that heat into lower level air.
As you go through the day, the surface heats up, which creates the unstable air starting early afternoon, and that can last until the night. Unstable air can exist at night because it takes time for the heat to radiate away from the surface. But in the morning, the surface has been losing that heat all night, and also not been receiving any heat from the sun for hours. So that’s why there is not unstable air in the mornings, and without unstable air, there are no thunderstorms.
Latest Answers