Equivalent temperature

For other similar terms, see Apparent temperature.

In atmospheric science, equivalent temperature is the temperature of an air parcel from which all the water vapor has been extracted by an adiabatic process.

Air contains water vapor that has been evaporated into it from liquid sources (lakes, sea, etc...). The energy needed to do that has been taken from the air. Taking a volume of air at temperature T and mixing ratio of r , drying it by condensation will restitute energy to the airmass. This will depend on the latent heat release as:

$T_e \approx T + \frac {L_v}{c_{pd}}r$

$\,L_v$ : latent heat of evaporation (2400 kJ/kg {at 25C} to 2600 kJ/kg {at -40C})

$\,c_{pd}$ : specific heat at constant pressure for air ( $\approx$ 1004 J/(kg·K))

Tables exist for exact values of the last two coefficients.

Bibliography

M Robitzsch, Aequivalenttemperatur und Aequivalentthemometer, Meteorologische Zeitschrift, 1928, pp. 313-315.
M K Yau and R.R. Rogers, Short Course in Cloud Physics, Third Edition, published by Butterworth-Heinemann, January 1, 1989, 304 pages. EAN 9780750632157 ISBN 0-7506-3215-1
J.V. Iribarne and W.L. Godson, Atmospheric Thermodynamics, published by D. Reidel Publishing Company, Dordrecht, Holland, 1973, 222 pages

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) Precipitation Water vapor

Convection	Convective available potential energy (CAPE) Convective inhibition (CIN) Convective instability Convective momentum transport Convective temperature (T_c) 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 (T_d) Dew point depression Dry-bulb temperature Equivalent temperature (T_e) Forest fire weather index Haines Index Heat index Humidex Humidity Relative humidity (RH) Mixing ratio Potential temperature (θ) Equivalent potential temperature (θ_e) Sea surface temperature (SST) Thermodynamic temperature Vapor pressure Virtual temperature Wet-bulb temperature Wet-bulb potential temperature Wind chill

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

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