Moisture in the Air MOISTURE IN THE AIR

Weather

• Present state of the atmosphere and current conditions

Climate

• Weather over a long period of time

• Example: Subtropical, desert, etc….

Factors that influence weather

• Temperature• Amount of moisture in air• Air pressure• Wind

Water Cycle

Precipitation

• Falling water out of sky• Water droplets stay small will stay suspended

in clouds• When water droplets reach > 0.2 mm they fall

out of sky as precipiation

Types of precipitation

• Rain, snow, sleet, and hail• Air temperature determines what will fall out

of sky• Above freezing (32oF) = rain• Below freezing = snow• Water freezes as ice = hail• Snow, then melts, then refreezes = sleet

Snow

Sleet

Freezing Rain

Humidity

• Amount of water in the air• Depends on temperature– High temp. – more water air can hold– Low temp – less water air can hold

– CHANGES IN HUMIDITY INDICATE CHANGES IN WEATHER

Relative Humidity

• Measure of amount of water vapor in air compared to total amount of water vapor it has room for at a particular temperature

• Stated as a percent• Example: 50 % humidity – air is only holding

50% of the water vapor that it can hold

Saturation

• When air is holding all the moisture it can at a particular temperature

• Saturated air = 100% humidity

Dew point

• Temperature at which air is saturated and condensation takes place.

Clouds

• Made of millions of water droplets• Form as humid air is cooled and reaches its

dew point and condenses• Condensed water vapor forms tiny drops of

water around dust particles in atmosphere• Millions get together = cloud

Clouds are classified into a system that uses Latin words to describe the appearance of clouds as seen by an observer on the ground.

Latin Root Translation Example

cumulus stratuscirrusnimbus

heap layercurl of hairrain

fair weather cumulus altostratuscirruscumulonimbus

Clouds: Five Types of Clouds1. High-Level Clouds: Usually found at greater than 20,000 ft.

Usually made of ice crystals

Examples include Cirrus, Cirrostratus

Clouds: Five Types of Clouds2. Mid-Level Clouds: Usually found between 6,500 and 20,000 ft.

Usually made of water droplets, but can be made of ice

Example is altocumulus

Clouds: Five Types of Clouds3. Low-Level Clouds: Usually found lower than 6,500 ft.

Low, lumpy clouds that produce weak to moderate precipitation

Examples include Nimbostratus and Stratocumulus

NSF North MississippK-8

Clouds: Five Types of Clouds4. Vertically developed: These clouds are thick and puffy and extend very far upwards

Examples include Cumulonimbus and Fair Weather Cumulus

Ordinary Cumulus clouds can quickly become Cumulonimbus clouds that start strong thunderstorms

Clouds: Five Types of Clouds5. Other: These are miscellaneous clouds

These clouds do not really fit into any category, and all have different characteristics

Examples include billow clouds, contrails, mammatus, orographic, and pileus