Types of Severe Weather
• Thunderstorms – Lightening – Thunder • Tornadoes • Hurricanes Thunderstorms
• Lightning is an electric discharge that occurs between a posi vely charged area and a nega vely charged area. Thunderstorms are very ac ve electrically.
• Thunder is the sound that results from the rapid expansion of air along the lightning strike. Tornadoes • A tornado is a small, spinning column of air that has high wind speeds and low central pressure and that touches the ground.
• A tornado starts out as a funnel cloud that pokes through the bo om of a cumulonimbus cloud and hangs in the air. The funnel cloud becomes a tornado when it makes contact with Earth’s surface.
Hurricanes
• How a Hurricane Forms A hurricane begins as a group of thunderstorms moving over tropical ocean waters. Winds traveling in two different direc ons meet and cause the storm to spin.
• Damage Caused by Hurricanes Hurricanes can cause a lot of damage when they move near or on to land. Wind speeds of most hurricanes range from 120 to 150 km/h. Hurricanes El Nino
• El Nino‐ a warm‐water event occurs in the tropical Pacific Ocean where winds shi & push warm surface water toward the west coast of South America
• Occurs once every 2 to 7 years & cause drama c climate changes around the Pacific Ocean & nearby areas such as droughts, floods, & tornadoes
• The only semi‐reliable way to predict an El Nino is to no ce the rising surface temperatures of the tropical parts of the Pacific Ocean
Weather Forecas ng
• Meteorologist‐ scien sts who study the causes of weather & try to predict it
• Meteorologists use informa on from many sources including local weather observers, weather balloons, satellites, & weather sta ons around the world Radio-sonde Satellites
Weather stations
Radar
Weather ship Supercomputer and weather buoys
Aviation Forecaster
National and International Shipping Global forecast services Forecast Services up to Weather forecasting 7 days ahead. Weather Forecas ng
• Sta on Models are shared from hundreds of loca ons and fed to the Na onal Weather Service
• The symbols are used to describe a weather condi on Weather Forecas ng Weather Accuracy
• Short‐range forecasts (12 to 72 hours) are quite accurate • Medium‐range forecasts (3 to 7 days) are now fairly reliable, and have shown significant improvement over the last 20 years as technology has improved. • Meteorologists also make long‐range predic ons, which aren’t as accurate but were once impossible to do Weather Tools
• Meteorologists use several tools to help them predict the weather including: – Weather Balloons – Satellites – Computers to interpret/calculate data – Weather Maps (from other sta ons, Na onal Weather Service, etc.) Weather Balloons & Satellites • Weather Balloons carry instruments high into the different layers of the atmosphere to collect weather data such as temperature, air pressure, & humidity
• The first weather satellite was launched in 1960
• Cameras on weather satellites can photograph Earth’s surface, clouds, storms, & ice & snow cover Computer Forecasts • Can be used to gather & interpret thousands of bits of data about temperature, air pressure, wind speed, & other factors quickly
• The computer starts with weather condi ons reported over a large area, then it works through many calcula ons to make a 12 hour , 24 hour, & 36 hour forecast
• As new informa on comes in, the forecast is adjusted Reading Weather Maps
• A weather map is a “snapshot” of weather condi ons at a par cular me in a par cular place
• There are many different types of weather maps such as computer or radar maps Weather Service Maps • Data from more than 300 local weather sta ons are complied at the Na onal Weather Service to help produce a map
• The curved lines on weather maps connect places where certain weather condi ons‐ temperature or air pressure‐ are the same Isobars & Isotherms • Isobar‐ lines joining places on the map that have the same air pressure – iso means “equal” & bar means “pressure” – the numbers on the isobars readings are measured in either inches of mercury or in millibars or both
Isobars
• Isotherms‐ lines joining places that have the same temperature – Iso means “equal” & therm means “heat” – will be labeled with the temperature in Fahrenheit, degrees Celsius, or both
Isotherms Newspaper Weather Maps • These are simplified maps produced by the National Weather Service for public use • Standard symbols on weather maps show fronts, areas of high & low pressure, types of precipitation, & temperature (given in Fahrenheit degrees)