Level of free convection

Level of free convection

The level of free convection (LFC) is the altitude in the atmosphere where the temperature of the environment decreases faster than the moist adiabatic lapse rate of a saturated air parcel at the same level.

The usual way of finding the LFC is to lift a parcel from a lower level along the dry adiabatic lapse rate until it crosses the mixing ratio line of the parcel: this is the lifted condensation level (LCL). From there on, follow the moist adiabatic lapse rate until the temperature of the parcel reaches the air mass temperature, at the equilibrium level (EL). If the temperature of the parcel along the moist adiabat is warmer than the environment on further lift, one has found the LFC.

Since the volume of the parcel is larger than the surrounding air after LFC by the ideal gas law (PV = nRT), it is less dense and becomes buoyant rising until its temperature (in E) crosses back the airmass one. If the airmass has one or many LFC, it is potentially unstable and may lead to convective clouds like cumulus and thunderstorms.

See also

* Atmospheric thermodynamics
* Free convective layer

External links

* [http://www.theweatherprediction.com/habyhints/309/ SKEW-T: A LOOK AT LFC]
* [http://amsglossary.allenpress.com/glossary/search?id=level-of-free-convection1 Level of free convection (LFC)] (Glossary of Meteorology)


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • level of free convection — The level at which a parcel of air lifted dry adiabatically becomes saturated. It would then rise moist adiabatically and being warmer than the surrounding atmosphere would continue to rise in a conditionally unstable atmosphere. The dry… …   Aviation dictionary

  • Convection — This figure shows a calculation for thermal convection in the Earth s mantle. Colors closer to red are hot areas and colors closer to blue are cold areas. A hot, less dense lower boundary layer sends plumes of hot material upwards, and likewise,… …   Wikipedia

  • Free convective layer — In atmospheric sciences, the free convective layer (FCL) is the layer of conditional or potential instability in the troposphere. It is a layer of positive buoyancy (PBE) and is the layer where deep, moist convection (DMC) can occur. On an… …   Wikipedia

  • Atmospheric convection — Conditions favorable for thunderstorm types and complexes Atmospheric convection is the result of a parcel environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to… …   Wikipedia

  • Maximum parcel level — The maximum parcel level (MPL) is the highest level in the atmosphere that a moist convectively rising air parcel will reach after ascending through the free convective layer (FCL) and reaching the equilibrium level (EL), near the tropopause. As… …   Wikipedia

  • Convective condensation level — The convective condensation level (CCL) represents the height where an air parcel becomes saturated when lifted adiabatically to achieve buoyant ascent. It marks where cloud base begins when air is heated from below to the convective temperature …   Wikipedia

  • Lifted condensation level — The lifted condensation level or lifting condensation level (LCL), represents the height at which an air parcel being lifted dry adiabatically will become saturated because of adiabatic cooling (caused by expansion) and condense into cloud. It… …   Wikipedia

  • Free surface — In physics a free surface is the surface of a body that is subject to neither perpendicular normal stress nor parallel shear stress,cite web |url=http://www.vishay.com/company/brands/measurements group/guide/glossary/freesurf.htm |title=Glossary …   Wikipedia

  • Rayleigh–Bénard convection — Bénard cells. Rayleigh–Bénard convection is a type of natural convection, occurring in a plane of fluid heated from below, in which the fluid develops a regular pattern of convection cells known as Bénard cells. Rayleigh–Bénard convection is one… …   Wikipedia

  • Cloud — For other uses, see Cloud (disambiguation). Cumulus cloudscape over Swifts Creek, Australia A cloud …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”