atmospheric motions in the vertical direction
In meteorology, convection refers primarily to atmospheric motions in the
vertical direction. As the earth is heated by the sun,
different surfaces absorb different amounts of energy and convection may
occur where the surface heats up very rapidly.
As the surface warms, it heats the overlying air, which gradually
becomes less dense than
the surrounding air and begins to rise.
||The bubble of relatively warm air
that rises upward from the surface is called a "thermal".|