WEATHER: TOPIC 7

What is an air mass?• An air mass is a large body of air in the

troposphere with similar characteristics of pressure, moisture and temperature

How are air masses characterized?

• Air masses are characterized by the regions in which they form over.– cA- Continental Arctic– cP- Continental polar– cT- Continental Tropic– mP- Maritime Polar– mT- Maritime tropical

What are the characteristics of a low pressure?

•The characteristics of a low pressure, also called cyclones are:

-Lowest pressure at the center -Winds blow toward the center-Winds circulate counterclockwise-Usually associated with stormy weather & heavy cloud cover

What are the characteristics of a high pressure?

• The characteristics of a high pressure, also called anticyclones are:– Highest pressure at the center – Winds blow away from the center– Winds circulate clockwise – Usually associated with calm and

clear weather

What is a front?

A front is a boundary or interface between two different air masses.

What are the different types of fronts?• Different types of clouds are:

– Cold front- boundary between advancing cold air mass and a warm air mass. The cold air pushes the warm air up like a wedge.

– A warm front- boundary between advancing warm air mass and a cold air mass. The warm air mass is forced to rise as it advances

– An occluded front- boundary between a cold air mass, warm air mass and a another cold air mass is sandwiches between two air mass. (A sandwich)

– A stationary front- when 2 different air masses remain in the same position

What is a storm? What are the different types of storms?

• A storm is a violent or severe disturbance of the atmosphere that usually creates dangerous and destructive conditions

• Different types of storms include mid-latitude cyclones, hurricanes, thunderstorms and blizzards.

What is a mid-latitude cyclone or cyclonic storm?

• A mid-latitude cyclone is a result from a low pressure system.

• These storms bring precipitation to the mid latitudes.

What is a hurricane and what are its characteristics?

• A hurricane is a low pressure system in the tropics in which winds blow at 74 mph or more

• They have rotating bands of precipitation, with a cloudless “eye” at the center.

• They are rated on a Safir-Simpson scale (which measure how much damage the storm causes).

What is a thunderstorm and what are the characteristics?

• A thunderstorm is a heavy rainstorm accompanied by thunder and lightening.

• Thunderstorms often form from uplifting of warm air. The clouds associated with thunderstorms are cumulonimbus clouds.

• They have 3 stages:• Developing stage• Mature stage• Dissipating stage

What is a tornado?• A tornado is a rapidly rotating extremely low

pressure funnel that hangs down from thunderstorm clouds

• Most tornadoes only last a few minutes. • 318 mph is the fastest recorded surface winds.• Most damage is actually caused by flying objects• Tornadoes are measured on a Enhanced Fajita

Scale (EF1, EF2, EF3, EF4….)

What is a blizzard?

• A blizzard is a storm with winds 35 mph or greater associated with considerable amounts of snow.