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?