Warm Up: How do fluids of different densities behave? Recall that a fluid can be either a liquid or a gas Materials: cardboard divider, plastic box, red food coloring, warm water, table salt, blue food coloring, cold water Predict what you think will happen when the divider is removed. Share your prediction Observe and Record the demonstration

Which weather factors produce changes in weather? Big Idea Which weather factors produce changes in weather?

Air Masses and Fronts Chapter 8, Section 3

Learning Goals S.6.4.e Students know differences in pressure, heat, air movement, and humidity result in changes in weather.

Key Questions What kinds of questions can you ask by looking at this picture?

Key Questions What kinds of questions can you ask based on this picture?

Key Questions What kinds of questions can you ask based on the picture?

Key Questions SWBAT describe the major types of air masses in North America, and how they move. SWBAT list the main types of fronts. SWBAT explain what type of weather is associated with cyclones and anticyclones.

Air mass A huge body of air that has a similar temperature, humidity, and air pressure

tropical Warm air masses formed in the tropics have low air pressure

polar Cold air masses with high air pressure

maritime Air masses that form over oceans. (Like the word ‘marina’)

continental Air masses that form over land

front The boundary where air masses meet

occluded Warm air mass is cut off from the ground

cyclone A swirling center of low air pressure

anticyclone High-pressure centers of dry air Cyclone – air moving upward Anticyclone – air moving downward

Types of Air Masses Four major types of air masses influence the weather in North America:

Types of Air Masses Maritime Polar – cool humid air

Types of Air Masses Continental Polar – cold air Maritime Polar – cool humid air Continental Polar – cold air

Types of Air Masses Continental Polar – cold air Maritime Polar – cool humid air Continental Polar – cold air Maritime Polar – cool humid air, pushed back out to sea

Types of Air Masses Continental Polar – cold air Maritime Polar – cool humid air Continental Polar – cold air Maritime Polar – cool humid air, pushed back out to sea Maritime Tropical– warm, humid air

Types of Air Masses Continental Polar – cold air Maritime Polar – cool humid air Continental Polar – cold air Maritime Polar – cool humid air, pushed back out to sea Maritime Tropical– warm, humid air Continental Tropical – hot, dry air

Types of Air Masses Continental Polar – cold air Maritime Polar – cool humid air Continental Polar – cold air Maritime Polar – cool humid air, pushed back out to sea Maritime Tropical– warm, humid air Maritime Tropical – warm, humid air Continental Tropical – hot, dry air

How Air Moves In the continental United States, air masses are commonly moved by the prevailing westerlies and jet streams.

How Air Moves Cold front – fast moving cold air mass overtakes a warm air mass Clouds will form If there is a lot of moisture, rain or snow will occur Sometimes, thunderstorms will happen if there is even more moisture Afterward, clear skies.

How Air Moves Cold front – fast moving cold air mass overtakes a warm air mass

How Air Moves Warm front – warm air mass overtakes a slow moving cold air mass If the air is humid, clouds and precipitation for several days. If the air is dry, there will be scattered clouds for several days. Afterward, it will be warm and humid.

How Air Moves Warm front – warm air mass overtakes a slow moving cold air mass

How Air Moves Stationary front – cold and warm air masses meet, but neither can move the other Warm air condenses into rain, snow, fog, or clouds. If the air mass doesn’t move, may lead to multiple days of heavy precipitation

How Air Moves Stationary front – cold and warm air masses meet, but neither can move the other

How Air Moves Occluded front – cold and warm air masses meet, but neither can move the other Warm air is pushed up to the top Cool air on the bottom will mix; temperature on the bottom will decrease. Warm air on top will condense, can lead to clouds or even rainfall.

How Air Moves Occluded front – cold and warm air masses meet, but neither can move the other

Cyclones and Anticyclones Cyclones and decreasing air pressure are associated with clouds, wind, and precipitation.

Cyclones and Anticyclones The descending air in an anticyclone generally causes dry, clear weather.

Key Questions What are the major types of air masses in North America, and how do they move?

Key Questions What are the major types of air masses in North America, and how do they move? Maritime tropical, continental tropical, maritime polar, and continental polar

Key Questions What are the major types of air masses in North America, and how do they move? Maritime tropical, continental tropical, maritime polar, and continental polar What are the main types of fronts?

Key Questions What are the major types of air masses in North America, and how do they move? Maritime tropical, continental tropical, maritime polar, and continental polar What are the main types of fronts? Cold fronts, warm fronts, stationary fronts, and occluded fronts

Key Questions What are the major types of air masses in North America, and how do they move? Maritime tropical, continental tropical, maritime polar, and continental polar What are the main types of fronts? Cold fronts, warm fronts, stationary fronts, and occluded fronts What type of weather is associated with cyclones and anticylcones?

Key Questions What are the major types of air masses in North America, and how do they move? Maritime tropical, continental tropical, maritime polar, and continental polar What are the main types of fronts? Cold fronts, warm fronts, stationary fronts, and occluded fronts What type of weather is associated with cyclones and anticylcones? Cyclones and decreasing air pressure – clouds, wind, and precipitation Anticyclones – dry, clear weather

Homework Workbook Chapter 8 Section 3