Level of free convection

Diagram showing an air parcel path when raised along B-C-E compared to the surrounding air mass Temperature (T) and humidity (Tw); see CAPE

The level of free convection (LFC) is the altitude in the atmosphere where an air parcel lifted adiabatically until saturation becomes warmer than the environment at the same level, so that positive buoyancy can initiate self-sustained convection.[1]

## Finding the LFC[edit]

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 saturated 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.[2][3]

## Use[edit]

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 (at EL) equals the surrounding airmass. If the airmass has one or many LFC, it is potentially unstable and may lead to convective clouds like cumulus and thunderstorms.

From the level of free convection to the point where the ascending parcel again becomes colder than its surroundings, the equilibrium level (EL), any air parcel gain kinetic energy which is calculated by its Convective available potential energy (CAPE), giving the potential for severe weather.[4]

## References[edit]

1. ^ "Level of free convection (LFC)". Glossary of Meteorology. American Meteorological Society. April 25, 2012. Retrieved 2021-08-04.
2. ^ "Determining Atmospheric Levels from a Skew-T Diagram". study.com. Retrieved 2021-08-04.
3. ^ Jeff Haby. "SKEW-T: A Look at LFC". www.theweatherprediction.com. Retrieved 2021-08-04.
4. ^ "Convective available potential energy". Glossary of Meteorology. American Meteorological Society. May 1, 2017. Retrieved 2021-08-04.

## See also[edit]

* Atmospheric convection
* Atmospheric thermodynamics

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Meteorological data and variables

General|

* Adiabatic processes
* Advection
* Buoyancy
* Lapse rate
* Lightning
* Surface solar radiation
* Surface weather analysis
* Visibility
* Vorticity
* Wind
* Wind shear

Condensation|

* Cloud
* Cloud condensation nuclei (CCN)
* Fog
* Convective condensation level (CCL)
* Lifted condensation level (LCL)
* Precipitable water
* Precipitation
* Water vapor

Convection|

* Convective available potential energy (CAPE)
* Convective inhibition (CIN)
* Convective instability
* Convective momentum transport
* Conditional symmetric instability
* Convective temperature (Tc)
* Equilibrium level (EL)
* Free convective layer (FCL)
* Helicity
* K Index
* Level of free convection (LFC)
* Lifted index (LI)
* Maximum parcel level (MPL)
* Bulk Richardson number (BRN)

Temperature|

* Dew point (Td)
* Dew point depression
* Dry-bulb temperature
* Equivalent temperature (Te)
* Forest fire weather index
* Haines Index
* Heat index
* Humidex
* Humidity
* Relative humidity (RH)
* Mixing ratio
* Potential temperature (θ)
* Equivalent potential temperature (θe)
* Sea surface temperature (SST)
* Temperature anomaly
* Thermodynamic temperature
* Vapor pressure
* Virtual temperature
* Wet-bulb temperature
* Wet-bulb globe temperature
* Wet-bulb potential temperature
* Wind chill

Pressure|

* Atmospheric pressure
* Baroclinity
* Barotropicity
* Pressure gradient
* Pressure-gradient force (PGF)

Velocity|

* Maximum potential intensity

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