gen-define-the-formation-of-clouds-and-give-one-short-worked-exa-fe3c

Define the formation of clouds and give one short worked example.

# Formation of Clouds **Definition:** Clouds form when water vapor in the air condenses into tiny liquid water droplets or ice crystals around condensation nuclei (dust, salt, or smoke particles). This occurs when air becomes **saturated** — unable to hold all its water vapor — typically through cooling to its **dew point temperature**. ## Main Formation Process: 1. Air containing water vapor rises (by convection, orographic lifting, or frontal systems) 2. Rising air expands and cools adiabatically 3. Temperature drops to the dew point 4. Water vapor condenses on nuclei 5. Billions of droplets/crystals = visible cloud --- ## Worked Example **Question:** Air at ground level has a temperature of 20°C and a dew point of 12°C. If it rises and cools at the dry adiabatic lapse rate of 10°C/km, at what altitude will a cloud begin to form? **Solution:** The cloud base forms when air temperature equals the dew point. - Temperature difference = 20°C - 12°C = 8°C - Air must cool by 8°C to reach saturation - Cooling rate = 10°C per km **Altitude of cloud base = 8°C ÷ 10°C/km = 0.8 km = 800 meters** **Answer:** The cloud will begin forming at an altitude of **800 meters** above ground level.