Bell-Ringer…AIRGet an index card from the

lab bench at the front of the room.

Put your name at the top of the card.

Then write down as many qualities of air as you can.

WeatherDay 14

The Big Idea…

Weather results from differences

in pressure, heat, air

movement, and humidity.

Essential Questions For Weather…1) Explain how water moves through the water cycle

2) Describe how relative humidity is affected by temperature and levels of water vapor.

3) Describe the relationship between dew point and condensation.

4) List three types of cloud forms.5) Identify four kinds of precipitation.6) Identify the four kinds air masses that influence weather in

the United States. 7) Describe the four major types of fronts.8) Explain how fronts cause weather changes. 9) Explain how cyclones and anticyclones affect the weather.10) Describe how lightning forms.11) Describe the formation of thunderstorms, tornadoes, &

hurricanes. 12) Describe the characteristics of thunderstorms, tornadoes, &

hurricanes.13) Explain how to stay safe during severe weather.14) Describe the different types of instruments used to take

weather measurements.15) Explain how radar and weather satellites help

meteorologists forecast the weather.16) Explain how to interpret a weather map.

Standards• S6E3 Students will recognize the

significant role of water in earth processes.

• S6E4 Students will understand how the distribution of land and oceans affects climate and weather.

• S6E5 Students will investigate the scientific view of how the earth’s surface is formed.

Things that make you go….hmmmmmmmm!

Have you ever wondered how the weather can change so quickly?

For example, the weather may be warm and sunny in the morning

and cold and rainy by afternoon.

Air Masses Change EVERYTHING!Changes in weather are caused by the movement and interaction of air masses. An air mass is a large body of air where temperature and moisture content are similar throughout. Air masses are characterized by their moisture content & temperature which is determined by the area over which the air mass forms. These areas are called source regions.Air masses are represented on maps by a two-letter symbol. The first letter indicates the moisture content that is characteristic of the air mass (where it forms). The second letter represents the temperature that is characteristic of the air mass.

Air Masses That Affect Weather in North America

Martitime (m)

Forms over water; wet

Continental (c)

Forms over land; dry

Polar (P)

Forms over the polar regions; cold

Tropical (T)

Develops over the Tropics; warm

Fronts: The area where two types of air masses meet; boundary between air masses of different

densities and usually different temperaturesCold Front: forms where cold air moves under warm air, which is less dense, & pushes the warm air up. (move quickly and bring thunderstorms, heavy rain, or snow)Warm Front: forms where warm air moves over cold, denser. (generally bring drizzly rain & are followed by clear & warm weather)Occluded Front: forms when a warm mass is caught between two colder air masses (has cool temps. & large amounts of rain)Stationary Front: forms when a cold air mass meets a warm air mass; brings days of cloudy wet weather

Air Pressure and Weather:• You may have heard a weather reporter on TV

or radio talking about areas of low pressure & high pressure. These areas of different pressure affect the weather.

• Cyclones: areas that have lower pressure than the surrounding areas do; areas where air masses come together, or converge, & rise; As the air in the center of a cyclone rises, it cools & forms clouds & rain. The rising air in a cyclone causes stormy weather.

• Anticyclones: areas that have high pressure; areas where air moves apart, or diverges, or sinks; As the air sinks, it gets warmer & absorbs moisture. The sinking air in an anticyclone brings dry, clear weather.

• By keeping track of cyclones & anticyclones, meteorologists can predict the weather.

Things that make you go….hmmmmmmmm!1. Explain the difference between front and air mass.

2. Explain the difference between cyclone & anticyclone.3. What kind of front forms when a cold air mass displaces a warm

air mass?(a) A cold front(b) A warm front(c) An occluded front(d) A stationary front

4. What are the major air masses that influence the weather in United States?

5. What is one source region of a maritime polar air mass?6. What are the characteristics of an air mass whose two-letter

symbol is cP?7. What are the four major types of fronts?8. How do the fronts cause weather changes?9. How do cyclones and anticyclones affect the weather?