Unit 2 – Lesson 2 Air Masses and Fronts

Unit 2 – Lesson 2 : 

Unit 2 – Lesson 2 Air Masses and Fronts

Air Masses : 

Air Masses A quick review!!!!!!!!!!!!!!!!!!!! Differences in air pressures cause air to move (winds) Air tends to move from areas of high pressure to areas of low pressure

What is an air mass? : 

What is an air mass? (def.) A very large body of air that takes on characteristic temperature and moisture of a region Usually thousands of km in diameter Form over a source region with relatively stable conditions Air masses are named for their source region

Types of Air Masses common in North America : 

Types of Air Masses common in North America Polar source region (colder air mass) (P) Tropical source region (warmer air mass) (T) Maritime source region (air mass forms over the ocean) (m) Continental source region (air mass forms over land) (c)

Slide 6: 

As you can see from this map, air masses are named for their source or sources. There are many different types of air masses that direct the weather patterns in the United States.

What is a Front? : 

What is a Front? In the world of weather, a front forms when two unlike air masses meet (cold and warm air masses) Can cause weather changes There are different types of fronts This unit will study only warm and cold fronts

Cold Front : 

Cold Front Cold air moves in to replace warmer air Warmer air, if moist, will form large cumulus and cumulonimbus clouds (the thunderstorm kind!!) Usually cold fronts cause short-lived, violent storms Temperature decreases after the front moves through an area Represented with blue line with triangles

Warm Front : 

Warm Front Warm air mass moves into replace a colder air mass Longer process to lift the colder, more dense air Clouds (much thinner, not puffy) form far ahead of the warm front Clouds near the base of the warm front are called STRATUS clouds These clouds are lower to the surface Usually cause lighter precipitation; longer in duration Represented on weather maps by a red line with red semi-circles

Conclusion : 

Conclusion This lesson taught about air masses and fronts. An air mass is very large body of air (usually thousands of miles) that takes on characteristic temperature and moisture of a region Fronts form when air masses of different temperature and moisture collide The learning activities will further explain these topics!