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A thermal column (or thermal) is a column of rising air
AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
 in the lower altitudes of the Earth's atmosphere
Earth's atmosphere

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. Dry air contains roughly 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% Carbon dioxide in the Earth's atmosphere, and trace amounts of other gases....
. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection
Convection

Convection in the most general terms refers to the movement of molecules within fluids . Convection is one of the major modes of heat transfer and mass transfer....
. The Sun warms the ground, which in turn warms the air directly above it.

The warmer air expands, becoming less dense
Density

The density of a material is defined as its mass per unit volume. The symbol of density is ....
 than the surrounding air mass.






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Thermal Column
A thermal column (or thermal) is a column of rising air
AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
 in the lower altitudes of the Earth's atmosphere
Earth's atmosphere

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. Dry air contains roughly 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% Carbon dioxide in the Earth's atmosphere, and trace amounts of other gases....
. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection
Convection

Convection in the most general terms refers to the movement of molecules within fluids . Convection is one of the major modes of heat transfer and mass transfer....
. The Sun warms the ground, which in turn warms the air directly above it.

The warmer air expands, becoming less dense
Density

The density of a material is defined as its mass per unit volume. The symbol of density is ....
 than the surrounding air mass. The mass of lighter air rises, and as it does, it cools due to its expansion at lower high-altitude pressures. It stops rising when it has cooled to the same temperature 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
Size

The word size may refer to how big something is. In particular:* Measurement* Dimensions: length, width, height, diameter, perimeter, area, volume...
 and strength
Power (physics)

In physics, power is the rate at which mechanical work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time....
 of thermals are influenced by the properties of the lower atmosphere (the troposphere
Troposphere

The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its water vapor and particulate....
). Generally, when the air is cold, bubbles of warm air formed by the ground heating the air above it, can rise like a hot air balloon. The air is then said to be unstable. If there is a warm layer of air higher up, an inversion can prevent thermals from rising high and the air is said to be stable.

Thermals on the Sun typically form hexagonal prisms (Bénard cells).

Thermals are often indicated by the presence of visible cumulus
Cumulus cloud

Cumulus clouds are a type of cloud with noticeable vertical development and clearly defined edges. Cumulus means "heap" or "pile" in Latin. These are often described as "puffy" or "cotton-like" in appearance, cumulus clouds may appear alone, in lines, or in clusters....
 clouds. When a steady wind is present thermals and their respective cumulus clouds can align in rows oriented with wind direction. Cumulus clouds formed by the rising air in a thermal as it cools and ascends, until the water vapor
Water vapor

Water vapor or water vapour , also aqueous vapor, is the gas phase of water . Water vapor is one Phase of the water cycle within the hydrosphere....
 in the air begins to condense into visible droplets. The condensing water releases latent heat
Latent heat

In thermochemistry, latent heat is the amount of energy in the form of heat released or absorbed by a chemical substance during a change of state of matter , or a phase transition....
 energy allowing the air to rise higher. Very unstable air can reach the level of free convection
Level of free convection

The level of free convection is the altitude in the Earth's atmosphere where the temperature of the environment decreases faster than the moist adiabatic lapse rate of a saturated air parcel at the same level....
 (LFC) and thus rise to great heights condensing large quantities of water and so forming showers or even thunderstorms.

Thermals are one of the many sources of lift
Lift (soaring)

Gliding is heavier than air flight without the use of thrust by soaring birds, flying and gliding animalss and by aircraft such as glider .As well as aerodynamic lift there are four principal other types of lift that are used: thermals, ridge lift, wave and convergence....
 used by soaring birds and gliders to soar
Gliding

Gliding refers to the descending flight of heavier-than-air craft, principally gliders s, hang gliders and paragliders. Technically, gliders, hang-gliders and paragliders are just different styles of glider used to pursue gliding and soaring for recreation, in the same way that sailboats and windsurfers share the lake and the wind....
.

A similar phenomenon can be seen in a lava lamp
Lava lamp

A lava lamp is a Novelties used for decoration rather than illumination; the slow chaos theory rise and fall of randomly-shaped blobs of wax is suggestive of lava, hence the name....
.

See also

  • Hot tower
    Hot tower

    A hot tower is a tropical cumulonimbus cloud that penetrates the tropopause, i.e. it reaches out of the lowest layer of the atmosphere, the troposphere, into the stratosphere....
  • Vertical draft
    Vertical draft

    An updraft or downdraft is the vertical movement of air as a weather related phenomenon. Commonly, one of two forces causes the air to move....
  • Atmospheric thermodynamics
    Atmospheric thermodynamics

    In the physical sciences, atmospheric thermodynamics is the study of heat and energy transformations in the earth?s atmospheric system. Following the fundamental laws of classical thermodynamics, atmospheric thermodynamics studies such phenomena as properties of moist air, formation of clouds, atmospheric convection, boundary layer meteorolo...

External links

  • - Thermal Structure and Behavior by Wayne M. Angevine