GEO E111 Lecture Notes - Lecture 18: Rain Shadow, Cloud Condensation Nuclei, Advection
Document Summary
Moist air rises to the condensation level (altitude where temperature is below dew point. Tiny water droplets condense around tiny particles such as dust, smoke particles and pollen grains and salt particles (condensation nuclei). The droplets merge and eventually become bigger and fall as rain. Super cooled cloud droplets may mould themselves around ice crystals before freezing to form hail. Rain experienced on the windward slopes of mountains or hills formed when moist air is forced to rise over a mountain or a hill. Moist air is forced to rise over a hill or mountain. The temperature and air pressure decreases making it to expand. Air cools due to decreased temperature and decreased pressure causing it to expand. The tiny water droplets in clouds merge and become too heavy to be suspended in air and fall as rain. Air proceeds to the leeward side with low moisture content.
