Weather

What do we know about weather?

How do people measure and predict the weather?

Meteorologist

• A scientist who studies the weather• What kind of tools do they use?

Thermometer

• Used to measure temperature• measures the kinetic energy of air

molecules• Fahrenheit & Celsius thermometers

Anemometer

• Measures wind speed• a system of gears converts the number of

turns per minute into wind speed

Hygrometer

• Measures humidity• the moisture in the air

Weather Vane

• Measures wind direction• changes in wind usually lead to change in

weather

Barometer

• Measures air pressure• high pressure = clear cool skies• low pressure = cloudy skies, moist air• extreme low pressure = stormy weather

Cloud Conditions

• Observing clouds can tell a lot about the weather

Cumulus

• White & puffy• fair weather

Cirrus

• High in the sky• white• thin & wispy• fair weather

Stratus

• Low in the sky• thick & gray• usually bring rain

Cumulonimbus

• Tower high into the sky• gray to black• Thunderstorms, hail, tornadoes• anvil shaped

How can rising air pressure lead to a prediction about weather?

Air Mass

• A large body of air that has the same temperature and humidity throughout

• take on the characteristics of the region over which they form

• 4 types in the the USA

Air Masses

– Categorized by moisture content and temperature– Moisture categories: m = maritime (wet) and c =

continental (dry)– Temperature categories: P (polar; cold), T

(Tropical; warm)

Continental Polar

• Cool dry weather

Continental Tropical

• Hot dry weather

Maritime polar

• Cool humid weather

Maritime Tropical

• Warm wet weather

Front

• Border where two air masses meet• most weather changes occur along a front• cold front = cold air mass moves under a

warm air mass creating cumulonimbus clouds

• warm front = a warm air mass moves over a cold air mass forming stratus clouds

What kind of air mass causes hot humid weather?

Climate

• The regular weather pattern for a region• precipitation & temperature determine

climate• seasonal patterns• all patterns are driven by the sun• proximity to the equator determines

temperature patterns

?????

• What is the cause of the seasons?• What are two major factors of climate?• What kind of climate would you find near

the equator?• What kind of climate would you find at the

poles?