1. The Weather Test Review

2. Air masses and fronts –Four types of air masses in N. America (Maritime means wet because the clouds formed over the ocean, continental means dry because the clouds formed over land, polar is cold and tropical is hot) Maritime tropical Maritime tropical Continental tropical Continental tropical Maritime polar Maritime polar Continental polar Continental polar

3. Warm Fronts Warm front-Front bringing warm air Warm front-Front bringing warm air Warm front - when a warm moist air mass rises above a cold air mass, a warm front forms. The gradient of the front is very shallow. Warm fronts occur at the forward edge of a depression (a low-pressure system). Warm front - when a warm moist air mass rises above a cold air mass, a warm front forms. The gradient of the front is very shallow. Warm fronts occur at the forward edge of a depression (a low-pressure system).

4. Cold Fronts Cold front-Front moving into an area bringing cold air (Cold air moves under warm air because it is more dense) Cold front-Front moving into an area bringing cold air (Cold air moves under warm air because it is more dense) Cold front - a cold front marks the advance of colder air undercutting warm air. The gradient of the cold front is steeper than that of a warm front, and the rainfall is usually heavier. Thunderstorms sometimes form along a cold front. Cold front - a cold front marks the advance of colder air undercutting warm air. The gradient of the cold front is steeper than that of a warm front, and the rainfall is usually heavier. Thunderstorms sometimes form along a cold front.

5. Stationary front A transition zone between two nearly stationary air masses of different density. When a warm or cold front stops moving, it becomes a stationary front. Once this boundary resumes its forward motion, it once again becomes a warm front or cold front. A stationary front is represented by alternating blue and red lines with blue triangles pointing towards the warmer air and red semicircles pointing towards the colder air. A transition zone between two nearly stationary air masses of different density. When a warm or cold front stops moving, it becomes a stationary front. Once this boundary resumes its forward motion, it once again becomes a warm front or cold front. A stationary front is represented by alternating blue and red lines with blue triangles pointing towards the warmer air and red semicircles pointing towards the colder air.warm frontcold frontwarm frontcold front

6. Occluded front when a cold front overtakes a warm front when a cold front overtakes a warm front A developing cyclone typically has a preceding warm front (the leading edge of a warm moist air mass) and a faster moving cold front (the leading edge of a colder drier air mass wrapping around the storm). North of the warm front is a mass of cooler air that was in place before the storm even entered the region. A developing cyclone typically has a preceding warm front (the leading edge of a warm moist air mass) and a faster moving cold front (the leading edge of a colder drier air mass wrapping around the storm). North of the warm front is a mass of cooler air that was in place before the storm even entered the region.cyclonewarm frontcold frontcyclonewarm frontcold front

7. Bad Weather-Cyclone Cyclones and decreasing air pressure are associated with storms and precipitation In low pressure areas as air rises it cools. As the air cools, the humidity in it begins to condense into tiny drops of water, or if it's cold enough, into tiny ice crystals. If there is enough water, or ice, rain or snow begin to fall. This is why low pressure is associated with bad weather. Cyclones and decreasing air pressure are associated with storms and precipitation In low pressure areas as air rises it cools. As the air cools, the humidity in it begins to condense into tiny drops of water, or if it's cold enough, into tiny ice crystals. If there is enough water, or ice, rain or snow begin to fall. This is why low pressure is associated with bad weather.

8. Good Weather- Anticyclone The pressure is high at the surface where air is slowly descending The pressure is high at the surface where air is slowly descending much too slowly to feel. And, this is going on over a large area, maybe a few hundred square miles. much too slowly to feel. And, this is going on over a large area, maybe a few hundred square miles. As air descends, it warms, which inhibits the formation of clouds. As air descends, it warms, which inhibits the formation of clouds. This is why high pressure is generally - but not quite always - associated with good weather. This is why high pressure is generally - but not quite always - associated with good weather.

9. Storms Thunderstorms and tornadoes form within large cumulonimbus (black and puffy) clouds usually in low pressure areas Thunderstorms and tornadoes form within large cumulonimbus (black and puffy) clouds usually in low pressure areas

10. Storm Safety During thunderstorms avoid touching metal objects During thunderstorms avoid touching metal objects

11. Hurricanes A hurricane begins over warm water in a low pressure area A hurricane begins over warm water in a low pressure area Hurricanes need wind speeds of at least 119 Kilometers per hour Hurricanes need wind speeds of at least 119 Kilometers per hour The eye of a hurricane is calm The eye of a hurricane is calm

12. Snow Snow falls when humid air-cools below 0C. Snow falls when humid air-cools below 0C. If you are caught in a snowstorm, try to find shelter from the wind. If you are caught in a snowstorm, try to find shelter from the wind. Lake effect snow is caused by cold air blowing over large lakes then over land Lake effect snow is caused by cold air blowing over large lakes then over land Be sure to wear sunglasses the snow causes glare Be sure to wear sunglasses the snow causes glare

13. Tornado A Tornado is a funnel-shaped cloud that touches the surface of the earth A Tornado is a funnel-shaped cloud that touches the surface of the earth About 800 tornados occur in the United States each year About 800 tornados occur in the United States each year During a tornado a basement is the safest place to be During a tornado a basement is the safest place to be

14. Floods Floods occur when so much water pours into a stream or river that it overflows its banks on either side of the channel Floods occur when so much water pours into a stream or river that it overflows its banks on either side of the channel Move to higher ground and stay away from flood waters Move to higher ground and stay away from flood waters Boil water from sources that have been flooded Boil water from sources that have been flooded

15. Predicting the Weather Meteorologists interpret weather information from local weather observers, instruments carried by balloons, satellites and weather stations around the world Meteorologists interpret weather information from local weather observers, instruments carried by balloons, satellites and weather stations around the world

16. Changes in weather technology Gathering weather data with satellites and weather balloons Using computers to make forecasts

17. El Nino is a weather pattern that forms in the tropical Pacific Ocean is a weather pattern that forms in the tropical Pacific Ocean Occurs every 2-7 years In the tropical Pacific, trade winds generally drive the surface waters westward. The surface water becomes progressively warmer going westward because of its longer exposure to solar heating. El Niño is observed when the easterly trade winds weaken, allowing warmer waters of the western Pacific to migrate eastward and eventually reach the South American Coast (shown in orange). The cool nutrient-rich sea water normally found along the coast of Peru is replaced by warmer water depleted of nutrients, resulting in a dramatic reduction in marine fish and plant life. Occurs every 2-7 years In the tropical Pacific, trade winds generally drive the surface waters westward. The surface water becomes progressively warmer going westward because of its longer exposure to solar heating. El Niño is observed when the easterly trade winds weaken, allowing warmer waters of the western Pacific to migrate eastward and eventually reach the South American Coast (shown in orange). The cool nutrient-rich sea water normally found along the coast of Peru is replaced by warmer water depleted of nutrients, resulting in a dramatic reduction in marine fish and plant life.trade windsdramatic reduction in marine fish and plant lifetrade windsdramatic reduction in marine fish and plant life

18. Local Winds (Sea and Land Breezes)

19. Weather maps Small lines at the end of the shaft that represents wind direction indicates wind speed Small lines at the end of the shaft that represents wind direction indicates wind speed Places with the same temperature are connected by isotherms Places with the same temperature are connected by isotherms Isobars are areas with the same air pressure Isobars are areas with the same air pressure