Clouds and Their Formation
What is a cloud?• A Cloud consists of condensed water vapor, ice and
dust (aerosols)
• There are three main types: cumulus, stratus, and cirrus
Requirements for cloud formation:
• Condensation Nuclei: small suspended particles or aerosols which the water vapor condenses on (ex: dust, pollen, sea salt)
• Saturated air (with water- relative humidity is 100%)
Recall: The Water Cycle
What Happens?
• As air rises it expands (less pressure on it) and cools
• It cools without any energy input or adiabatically
• It reaches the dew point, and the water vapor condenses
• The opposite is true in a sinking air mass- it compresses and warms
• Ice crystals can form if the atmospheric temperature is below 0 ºC
Draw this out:
Let’s Sum up:
• Create a flow chart showing the steps in cloud
Do Now
• Can you make a cloud in a bottle? If so, how would you do it? If not, why can’t you do it?
• cloud types (see diagram)
• dew: water condenses on ground surface
• frost: water condenses and freezes on surface
• fog: cloud at ground level
• Water droplets coalesce (grow together) and get too heavy to stay in the air- so they fall as rain
• types of precipitation include: rain, drizzle, freezing rain(reaches a cold pocket of air and freezes upon contact with a surface), sleet (ice pellets), hail (ice spheres that begin in a cloud as snow or rain and melt and gather moisture as they fall), and snow (deposits)
When will it Rain?