How are heat flow and air movement related to the formation of thunderstorms?
1 Answer
Both are integral for the formation of thunderstorms.
Explanation:
I think the best way to answer this is to just explain how a thunderstorm is formed.
First, you need unstable air. Unstable air usually has an environmental lapse rate that is steeper than the average environmental lapse rate (6.0 degrees/km).
A parcel of air then needs to be lifted. It can be lifted by one of the 5 lifting processes (orographic, convection, convergence, frontal or mechanical). Regardless of which process occurs the parcel of air is going to cool at the dry adiabatic lapse rate (10 degrees/km). Eventually, dependent on the humidity of the parcel, the temperature of that parcel is going to reach the dew point (meaning that the relative humidity will be 100%). This point is called the lifted condensation level (lcl) and is where cloud starts forming.
If the parcel continues to be lifted it is now going to be cooled at the saturated adiabatic lapse rate (5.0 degrees/km). It is a shallower lapse rate because the process of condensation releases latent heat (heat trapped in water vapor from the process of evaporation) as sensible heat (heat you can feel). So now the parcel of air is cooling at a slower rate than the environment. Due to this at some point that rising parcel of air is going to become warmer than the surrounding air and it will then be buoyant and keep rising on its own. This is know as the level of free convection (LFC).
Eventually, the environment lapse rate is going to become negative (gets warmer the higher you go), and that rising parcel of air will lose it's buoyancy. This is the equilibrium level (EL). The air parcel does not stop rising here because from the LFC to the EL the air parcel will have picked up a lot of inertia and it will continue rising until this inertia is spent. This will be the top of the cloud. If the cloud is big enough it will be a cumulonimbus and a thunderstorm will occur.
In short, upward motion of air and heat flowing from water vapor into the environment.
