III. Section 3.3 Vertical air motion can cause severe storms

Transcription

1 III. Section 3.3 Vertical air motion can cause severe storms A. Thunderstorms form from rising moist air Electrical charges build up near the tops and bottoms of clouds as pellets of ice move up and down through the clouds A charge sparks from one part of a cloud to another or between a cloud and the ground Lightning a spark of electricity and causes a bright flash of light Air around lightning is briefly heated to a temperature hotter than the surface of the Sun This fast heating produces a sharp wave of air that travels away from the lightning When the wave reaches you, you hear it as a crack of thunder Thunderstorm is a storm with lightning and thunder

2 B. Formation of Thunderstorms Rising humid air forms a cumulus cloud. The water vapor release energy when it condenses into cloud droplets. This energy increases the air motion. The cloud continues building up into the tall cumulonimbus of a thunderstorm Ice particles from in the low temperatures near the top of the cloud. As the ice particles grow large, they being to fall and pull cold air down with them. This strong downdraft brings heavy rain or hail the most severe stage of a thunderstorm The downdraft can spread out and block more warm air from moving upward into the cloud. The storm slows down and ends. Can form at a cold front or within an air mass Conditions that produce thunderstorms occur almost daily during part of the year

3 C. Effects of Thunderstorms Flash Floods o Can be strong enough to wash away people, cars, and even houses o One thunderstorm can produce millions of liters of rain o Water can cover the ground or make rivers Winds Hail o Can be very strong during a thunderstorm o Can blow in bursts and exceed 270km/hour (170mph) o Causes nearly $1 billion in damage to property and crops in the US every year o Can wipe out entire fields of a valuable crop in a few minutes o Can damage roofs and kill livestock Lightning o Can kill or seriously injure any person it hits o Can spark dangerous forest fires

4 Thunderstorms Lightning: sudden spark or electrical discharge typically caused by the build up of positive charges on Earth with negative charges within the air.» Cloud to cloud» Cloud to ground» Ground to cloud (rare) Thunder is caused as air is superheated (30,000ºC), expands, and explodes.» Thunder is the sound wave created from the explosion.» Because sound travels slower than light, thunder always comes after lightning not the other way around.

5 D. Tornadoes form in severe thunderstorms Tornado is a violently rotating column of air stretching from a cloud to the ground Moves along the ground in a winding path underneath the cloud The column may even rise off the ground and then come down in a different place May become visible when water droplets appear below the cloud in the center of a rotating column May lift dust and debris from the ground, so the bottom of the column becomes visible May form a serious of tornadoes or even a group of tornadoes all at once How tornadoes are formed!!!

6 Tornadoes Tornadoes can form in any situation that produces severe weather. Typically form during the Spring & Summer under the same conditions as those of a thunderstorm. Tornado formation Warm, moist air flows in at the bottom of a cumulonimbus cloud & rapidly moves upward generating a low pressure area inside the cloud. The warm air begins to rotate due to winds within the cloud blowing in different directions: The result is the cloud begins to spin like a top. As part of the cloud descends to touch the ground, a tornado or funnel cloud is generated with winds up to 340 mph.

7 The Fujita Scale Used to determine the severity of a tornado. Based on the amount of damage created as well as the wind speed. F-0: Gale tornado, mph winds F-1: Moderate tornado, mph winds F-2: Significant tornado, mph winds F-3: Severe tornado, mph winds F-4: Devastating tornado, mph winds F-5: Incredible tornado, mph winds Tornado alley Located in the Midwest region of the U.S. & is known for the development of tornadoes. Includes the states of S. Dakota, Iowa, Nebraska, Kansas, Oklahoma, and Texas.

8 E. Effects of Tornadoes Can cause damage as the bottom of the tornado moves along the ground Can also pick up and slam dirt and small objects into buildings or anything else in the tornado s path Most common tornadoes are small and last only a few minutes Larger ones are less common but have stronger winds and last longer 20% are strong enough to knock over large trees, lift cars off the ground, and tear the roof off houses Moves along with its thunderstorm National Weather Service issues a tornado watch when the weather condition might produce tornadoes. A warning is issued when a tornado has been detected

9 Winter storms Lake effect snow Caused as cold dry air moves across a warmer body of water. It becomes more humid as water vapor evaporates from the lake surface. The air reaches land & cools causing lake-effect snow to fall.» Great Lakes area (Michigan, Wisconsin, & Buffalo, NY)

10 IV. Section 3.4 Weather forecasters use advanced technologies A. Weather data come from many sources Weather report can show conditions in your area and also in the region around you Meteorologist is a scientist who studies weather Looks at past and current conditions. They use many forms of technology to gather data Types of technology that is used to collect weather data o Radar stations locate clouds and measure their heights. Doppler radar can detect air motion and precipitation o Airplanes and ships can carry instrument packages that make measurements wherever they go

11 o Ground stations hold instruments that measure air pressure, temperature, dew point, precipitation, wind speed, wind direction, and cloud cover o Satellites orbit Earth above the atmosphere. Images ca show cloud cover, warm and cool regions, and invisible water vapor o Weather balloons make important measurements of the air at different altitudes as they carry instruments high into the stratosphere o Weather buoys record the weather far from cities. They also measure conditions in the ocean that affect the atmosphere TIROS-1: 1 st weather satellite launched in 1960 Located within the exosphere Carries a variety of scientific weather instruments Cameras: to take pictures of various weather factors. Temperature gauges, Radiation detectors, humidity detectors, wind speed gauges, etc.

12 B. Weather data can be displayed on maps Scientists use computers to record and use the enormous amount of data gathered Meteorologists use maps to display a lot of information at once C. Air pressure on weather maps Isobar is a line that connects places that have the same air pressure Each isobar represents a different air pressure value

13 Each is labeled with the air pressure for that whole line in units called millibars Shows pressure patterns which determine winds Lines close together show a big difference in air pressure. Expect strong winds here. Lines are far apart where the air pressure is almost even. Expect calm air or light breezes near the high Information shown on a weather map Precipitation type Fronts Temperature Air pressure Cloud cover High pressure and low pressure area

14 D. Forecasters use computer models to predict weather Instruments can only measure the current weather conditions Forecasters can make some predictions from their own observations If they have information from other places, the forecasters might be able to tell where the warm front is already and how fast it is moving They might be able to predict how soon it will arrive and even how warm the weather will be after the front passes

15 Computers have become an important tool for forecasting weather When weather stations send in data computers can create maps right away They combine many types of date to forecast what might happen next Scientists study the computer forecasts, then apply their knowledge and experience to make weather predictions Forecasting the weather is complicated The farther in advance a forecast is made, the more time there is for small differences between the predicted and the actual weather to add up Up to 3 days in advance are the most accurate

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