Chapter 5 Clouds

What are the Basic Elementsof Weather & Climate

(list 6)

Wind

Temperature

HumidityClouds

PrecipitationPressure

Precipitation

List 6 forms of precipitation:

What is graupel?

Clouds: • A visible aggregate of minute droplets of

water or tiny ice crystals (or both).

For Clouds to form, TWO conditions must exist:

1. Air is lifted, cooled adiabatically, until the air is SATURATED. Then water vapor can

condense into water droplets

What do all these pictures have to do with clouds?

Cloud Condensation Nuclei

2. Water vapor needs to condense (stick) onto a SURFACE.

A “surface” can be microscopic dust particles, smoke, salt, pollen, volcanic ash, soot from combustion or forest fires.

Without the condensation nuclei surface, the air needs to be greater than 100% humidity or very, very low temperatures (so the water vapor has very little KE and the particles can slow down enough to collide and stick together.

2 types of condensation nuclei

Hygroscopic nuclei• “Water-seeking”• Effective sites for water

vapor to condense into droplets.

• Form larger water droplets

• Example: salt particles

Hydrophobic nuclei• “water-repelling”• Not efficient for forming

water droplets • only if the relative humidity

reaches 100%• Form smaller droplets

Initially, cloud droplet formation is

rapid,but it slows as the

water vapor in the air is used up

The size of cloud droplets can vary.

It takes about a million cloud

droplets to form a single raindrop.

Classification Cloud Types Height Composition Description

High Clouds Prefix: ____________ _____________meters

Middle Clouds Prefix: ___________ ____________meters

Low Clouds Prefix: ____________ _____________meters

Clouds of Vertical

Development

Cloud Types: height and form

Pg. 134

Cirrus Clouds

Cirrostratus

Cirrocumulus

AircraftContrails:

Condensation trails of ice crystals

Altocumulus Altostratus

Nimbostratus

Cumulus Clouds

Cumulonimbus:Dark, dense, towering clouds with anvil-tops that reach heights of 30,000 ft. and produce thunderstorms, hail and tornados.

• Why are high clouds always so thin

compared to low clouds?

Lenticular

Clouds