MeteoReport.docx

\"One of the most significant facts in physical geography is that the only way in which large masses of air can be cooled to the dew point temperature is by expansion as the air masses rise.\" (McKnight\'s Physical Geography) **[Adiabatic Cooling and Warming]** \- Changes in temperature that occur...

\"One of the most significant facts in physical geography is that the only way in which large masses of air can be cooled to the dew point temperature is by expansion as the air masses rise.\" (McKnight\'s Physical Geography) **[Adiabatic Cooling and Warming]** \- Changes in temperature that occur in air as it rises and falls. Since no heat is exchanged, the temperature of the system changes due to the work done, leading to either compression (temperature increases) or expansion (temperature decreases). Adiabatic Cooling: -rising air expands due to reduced pressure -cools Adiabatic Warming: -sinking air compresses due to greater pressure -warms **[Adiabatic Cooling]** Large masses of air are cooled to the dew point by adiabatic cooling  Adiabatic cooling is the most prominent mechanism for developing clouds and the production of rain. **How fast does the air cool and warm?** Rate depends on whether the air is unsaturated or saturated. **[Dry Adiabatic Rate]** Air is not necessarily \"dry\", it is just [not saturated.] Rate at which an [unsaturated] parcel of air cools [as it rises] 10°C/1000m Descending air also warms at the dry adiabatic lapse rate **[Lifting Condensation Level]**  Altitude at which rising air cools sufficiently to reach 100% RH at the dew point temperature. Condensation begins - Clouds Form **[Lifting Condensation Level]** **[Saturated Adiabatic Rate]**  Rate of cooling is less than DALR because latent heat of condensation is released as water condenses. **[Saturated Lapse Rate]** Rate at which a saturated parcel of air cools as it rises Occurs after air rises above LCL [Descending air always warms at the dry adiabatic rate] As air descends it warms. Warm air can hold more moisture, so RH decreases. Thus descending air is always unsaturated