LCL, or lifting condensation level, is defined as:

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Multiple Choice

LCL, or lifting condensation level, is defined as:

LCL is the height where a rising air parcel becomes saturated and clouds begin to form. As air rises, it cools and expands. Condensation starts when the parcel's temperature reaches its dew point, reaching 100% relative humidity. That level is the lifting condensation level, the cloud base for the parcel. A handy way to think about it is that the closer the surface temperature is to the dew point, the lower the LCL; if the temperature equals the dew point at the surface, the LCL is at the surface. A rough rule of thumb is LCL (in meters) ≈ 125 × (T − Td) in Celsius, where T is the surface temperature and Td is the surface dew point. The other options don’t describe this saturation process: the height at which surface air becomes unstable refers to buoyancy and instability, not cloud formation; the tropopause is an upper boundary of the troposphere, not the cloud base; and the base height of high clouds is determined by conditions higher in the atmosphere and isn’t the point where a rising parcel first saturates.

LCL is the height where a rising air parcel becomes saturated and clouds begin to form. As air rises, it cools and expands. Condensation starts when the parcel's temperature reaches its dew point, reaching 100% relative humidity. That level is the lifting condensation level, the cloud base for the parcel.

A handy way to think about it is that the closer the surface temperature is to the dew point, the lower the LCL; if the temperature equals the dew point at the surface, the LCL is at the surface. A rough rule of thumb is LCL (in meters) ≈ 125 × (T − Td) in Celsius, where T is the surface temperature and Td is the surface dew point.

The other options don’t describe this saturation process: the height at which surface air becomes unstable refers to buoyancy and instability, not cloud formation; the tropopause is an upper boundary of the troposphere, not the cloud base; and the base height of high clouds is determined by conditions higher in the atmosphere and isn’t the point where a rising parcel first saturates.

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