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Name: _____________________________________________ Date: __________________________ Core: ___________ Weather and Storms Cyclones vs. Anticyclones: Cyclones: A swirling center of _________________ pressure. As warm air in the center of the cyclone rises, the air pressure _____________________________. Cooler surrounding air blows towards the low pressure area, creating winds that spiral inwards, towards the center of the system. As the air rises, it _____________________, forming clouds, winds and __________________________________. Anticyclones: The opposite of a cyclone. This is a center of dry, __________________ pressure air. Winds spiral outwards from the center, moving towards areas of lower pressure. As the air moves down and out from the center of pressure, it warms and the relative humidity drops, causing dry, _______________________ weather. Types of Precipitation: Type of Precipitation Size Formation Occurs… Notes: Rain Sleet Freezing Rain Snow Hail Storms: Storm: A violent disturbance in the _________________________________. Storms involve sudden changes in __________________________________, which cause rapid air movements. Severe Storm Types: Thunderstorms: A fairly small storm, often accompanied by heavy _______________________________, and frequent thunder and _________________________. >Formation: Thunderstorms form in large ___________________________________ clouds, most often on hot, humid afternoons/evenings. The warm, ___________________ air rises rapidly, causing it to quickly cool, and form dense thunderheads. >Lightning and Thunder: During a thunderstorm, areas of _______________________ and _______________________ electrical charges build up in the clouds. -­‐Lightning: A sudden spark (electrical discharge) that occurs as the built-­‐up electrical charges jump between parts of the cloud, between nearby clouds, or between the cloud and the ground. A single lightning bolt can heat the air around it to as much as 30,000oC (HOTTER THAN THE SURFACE OF THE SUN!!) -­‐Thunder: Since lightning heats the air around it so quickly, the air expands suddenly and explosively – thunder is actually the sound of the explosion! Since light travels much faster than sound, you see the lightning before you hear the thunder! >Damage and Safety: Thunderstorms can cause sever damage to an area. They can __________________ low-­‐lying areas, take down trees, start forest fires, even strike humans with lightning bolts. The safest place to be during a thunderstorm is indoors (away from things that can conduct ____________________________). If you are caught outside during a thunderstorm, you should avoid __________________, _____________________ and bodies of ______________________. Tornadoes: A rapidly whirling, __________________________________ cloud that reaches down from a storm cloud to touch the Earth’s ______________________________. Tornadoes are usually brief, but they can cause lots of destruction, reaching winds speeds of up to ________________ km/hr. >Formation: Tornadoes most commonly develop in thick, _____________________________________ clouds – the same ones that produce thunderstorms. They occur most often in spring and early summer, often in the late afternoon, when the ground is its warmest. Typically, a warm, _____________________ air mass meets a cold, ______________ air mass. When the air masses meet, the ___________________ air moves underneath the ____________________ air, forcing it to rise. A squall line of thunderstorms forms, which can produce ten or more tornadoes! >Tornado Ally: Tornadoes occur in the U.S. more than any other country. Air movements in the Great Plains (meeting of air masses from the Gulf of Mexico, and Canada) results in “tornado ally” which is an area with frequent tornadoes. >Damage and Safety: Tornadoes cause damage through both their strong winds, and the flying debris they create. Tornadoes are ranked on the Fujita scale, which is based on _______________________________, and the amount of _____________________ they create. The scale ranges from light damage (F0) to extreme damage (F5). If a tornado warning is announced for your area you should move in a storm shelter or the basement of a sturdy, well-­‐built building. Hurricanes: A tropical __________________________ that has winds of ________________ km/hr or higher. Most hurricanes are about _______________ km across. Hurricanes form over the Atlantic, Pacific and Indian oceans. > Formation: A hurricane begins over warm ocean water as a ___________ pressure area, or a tropical disturbance. If the tropical disturbance grows in size a strength it will become a tropical storm, which may then become a hurricane. A hurricane draws it energy from the warm, ___________________ air above the ocean’s surface. As this air rises and forms ______________________, more air is drawn upwards into the system. Winds begin to spiral towards the area of _______________ pressure at the center. 1) Warm, moist air rises around the center and forms spiraling bands of clouds. 2) The air flows outwards near the top of the hurricane. 3) Cool, dry air sinks in the center, creating the eye of the hurricane. > Movement: Hurricanes last longer than other types of storms – usually a week or more. During that time they often travel quite a long distance. Once a hurricane reaches land it no longer has access to the warm, ___________________ air that it draws its energy from, and as a result it gradually loses ____________________, and slowly dies out. > Damage and Safety: Hurricanes bring high waves, severe flooding and wind damage. They cause “storm surges” which can raise the level of water up to over __________ meters its normal height. If a hurricane warning is announced for your area, that means that hurricane conditions are expected within the next __________ hours. The best thing to do is evacuate the area and move to higher ground, further from the coast. Snowstorm: Times of prolonged snow, and wind. >Lake-­‐Effect Snow: Land near large lakes cools much faster than the water in the lakes. As a cool, ___________ air mass moves over the lake it picks up water vapor and _________________ from the lake. When this air mass reaches the land it rapidly cools and the water vapor condenses into snow – lake effect snow. >Damage and Safety: High winds during a snowstorm, and the weight of the snow itself can lead to downed trees and power lines and even roof cave-­‐ins. If you are caught during a snowstorm try to find shelter.