1.1.2.2. Initiation of convection – how thunderstorms start (daytime heating, fronts, etc)

  • 3 months ago
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  • Author: SW101

Initiation of convection

On a warm day, convection begins when the air close to the surface warms enough to become buoyant and start rising. This process is called free convection. The temperature at which free convection begins is called the convective temperature. When the convective temperature is reached on a clear, hot and humid day, the atmosphere becomes widespread explosive development of thunderstorms begins. The height at which moisture in the rising air condenses is called the convective condensation level (CCL).

Air parcels at the surface buoyantly lift and require no other mechanisms to start lifting. There are other ways of getting air parcels at the surface to begin lifting, even if the air near the surface is stable (it is below convective temperature). There needs to be another other lifting mechanisms that pushes the air to a height where it becomes buoyant and begins to rise. The height at which moisture in the rising air condenses is now called the lifted condensation level (LCL)