Thermal
A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically.
Thermals on Earth
The Sun warms the ground, which in turn warms the air directly above.[2] The warm air near the surface expands, becoming less dense than the surrounding air. The lighter air rises and cools due to its expansion in the lower pressure at higher altitudes. It stops rising when it has cooled to the same temperature, thus density, as the surrounding air.
Associated with a thermal is a downward flow surrounding the thermal column. The downward-moving exterior is caused by colder air being displaced at the top of the thermal.
The size and
Thermals are often indicated by the presence of visible isolated
The condensing water releases latent heat energy allowing the air to rise higher. Very unstable air can reach the level of free convection (LFC), rising to great heights, condensing large quantities of water and forming convective clouds causing showers or even thunderstorms. The latter are dangerous to any aircraft flying through or nearby.
Thermals are one of the many sources of
.Thermals beyond Earth
Thermals are also seen elsewhere in the solar system. On
See also
References
- ^ "Glider Flying Handbook, FAA-H-8083-13A" (PDF). FAA government handbooks. U.S. Dept. of Transportation, FAA. 2003. pp. 9–6, 9–7. Retrieved 21 January 2021.
- ISBN 0-7136-4226-2.
External links
- What do thermals look like? - Thermal Structure and Behavior by Wayne M. Angevine
- Time-lapse video of clouds caused by thermals forming and decaying