Essential Question: What causing the changing weather? Key Concept: Weather includes temperature, wind, precipitation, and cloud cover. These factors constantly change because the atmosphere changes.

What is the WEATHER? -the condition of the atmosphere at a certain time and place. -Weather changes whenever air with different properties moves over an area. -This includes the interactions between air masses, fronts, and pressure systems.

-A large body of air that has the same properties throughout. Air Masses: -A large body of air that has the same properties throughout. -Can be WARM or COLD depending on where they formed. Tropical Region Polar Region Warmer Cooler Over Water Over Land Wetter Dryer - Temperature and amount of moisture in air mass affect the weather as the air mass moves.

-A boundary between 2 air masses. Fronts: -A boundary between 2 air masses. -A warm air mass meets a cold air mass at a front. 4 types of fronts: - warm front - cold front - stationary front - occluded front The type of weather depends on how the two masses interact.

-Forms when warm air mass bumps into a cold air mass. 1. Warm Fronts: -Forms when warm air mass bumps into a cold air mass. -The warm front slides up and over the cold air. -Contains wetter air than cold front. -As the humid air rises, clouds are likely to form and precipitation might form. -Brings drizzle or light rain followed by warm, clear weather.

-Forms when cold air mass pushes under a warm air mass. 2.Cold Fronts: -Forms when cold air mass pushes under a warm air mass. -This forces the warm air to rise quickly which causes tall storm clouds form. -Brings heavy rain, thunderstorms, and snow and leave colder and clearer weather. - Whether it brings snow or rain depends on temperature.

http://www.suu.edu/faculty/colberg/hazards/weather/05_cnWfronts.html

-Forms when a warm air mass and cold air mass meet and stop moving. 3.Stationary Fronts: -Forms when a warm air mass and cold air mass meet and stop moving. -Usually brings light winds and precipitation, sometimes lasting for several days.

-Forms when a warm air mass is caught between two colder air masses. 4. Occluded Front: -Forms when a warm air mass is caught between two colder air masses. -Warm air cannot move, so it is forced to rise. -Brings strong winds and cooler temperatures. It can also bring long periods of rain or snow.

High and Low Pressure Systems Warm air rising and cold air sinking combined with the spinning of Earth causes the air to spin forming high and low pressure regions

High Pressure System: -signals fair weather -winds circulate around in a clockwise direction -moves towards lower pressure areas Low Pressure Systems: -signals rainy and stormy weather -winds circulate counterclockwise

Storms = Severe Weather - Caused by pressure differences and rapid air movement. - 1 type of storm can lead to another type of storm later. Examples: Thunderstorms, Tornado, Hurricanes

There is always weather. Weather is a condition of Earth's atmosphere. It does NOT need to be stormy. It also includes sunny days, showers, humid days, clear skies, and cold temperature.

Summary: What is weather. Why does weather change. What are air masses Summary: What is weather? Why does weather change? What are air masses? Describe the different types of fronts. What are the differences between high and low pressures. How do storms form and give some examples.