Weather Vocabulary Terms • Adiabatic Cooling • Air Masses • Anemometer • Barometer • Blizzards & Winter Storms • Category 5 Hurricane • Cloud Types • Cold Front • Conditions For Severe Weather • Convection Cells • Convergence And Low Pressure Air Masses • Doppler Radar And Doppler Effect • Downdrafts • Drought • Flooding • Front Types • Frontal Wedging • Gusty Surface Winds • Hurricanes And Hurricane Formation • Hygrometer 21. Jet Streams 22. Low Vs. High Pressure Systems 23. Mass Evacuation 24. Meteorology 25. Reasons For The Seasons 26. Saffir-Simpson Hurricane Scale 27. Severe Weather & Seasonal Variations 28. Severe Weather & Societal Impacts 29. Severe Weather Advisory 30. Severe Weather Types World-Wide 31. Severe Weather Warning 32. Severe Weather Watch 33. Social Impacts 34. Storm Surge 35. Thunderstorm 36. Tornado 37. Tornado Safety Measures 38. Updrafts 39. Weather 40. Weather Maps P.335
Adiabatic Cooling • Cooling that occurs by a change in pressure as an air mass rises • Heat is not lost, but the temperature of the air drops as it rises in altitude • Usually, clouds form as a result of the cooler temperatures • Responsible for cloud formation as air rises to go over a mountain • http://www.youtube.com/watch?v=XH_M4jItiKw • Windward side gets the rain, leeward side has dry weather (rain shadow desert)
Air Masses • Large volume of air with characteristics affected by the location where it formed • Maritime - moist • Continental - dry • Polar - cold • Tropical - warm • 4 main air masses affect U.S. weather patterns
Anemometer • device used for measuring wind speed, and is a common weather station instrument • derived from the Greek word anemos, meaning wind
Barometer • instrument that is used to measure air pressure and predict changes in the weather • Low pressure brings clouds and bad weather • High pressure brings clear air and no clouds (water droplets for clouds cannot form under high pressure conditions)
Blizzards & Winter Storms • air mass of cold, dry, Canadian air moves south and interacts with a warm, moist air mass moving north from the Gulf of Mexico • The point where these two air masses meet is called a front • A blizzard is defined by winds blowing at 35 miles per hour or higher. One of the reasons why blizzards are so dangerous is the reduced visibility due to snow flying everywhere from the fast wind.
Category 5 Hurricane • Most catastrophic rating of hurricanes on Saffir-Simpson Scale • Example: Katrina in New Orleans 2005 • http://www.weather.com/video/hurricane-categories-make-a-difference-38272
Cloud Types • large collection of very tiny droplets of water or ice crystals. The droplets are so small and light that they can float in the air. • high clouds, middle clouds, low clouds, and vertical clouds • Latin RootTranslation cumulus - heapstratus - layercirrus - wispynimbus - rain
Cold Front • the transition zone where a cold air mass is replacing a warmer air mass • Warmer air moves upward quickly and can produce dangerous cumulonimbus cloud • Most dangerous and quickly changing type of weather front
Conditions for Severe Weather • Types of severe weather vary, depending on the latitude, altitude, topography, and atmospheric conditions because seasons vary by location on the planet • Tornado's, hurricanes, floods and blizzards are considered types of severe weather
Convection Cells • density differences result in rising and/or falling currents • Can produce strong and sudden storms
Convergence and Low Pressure Air Masses • Low pressure system is an area where the atmospheric pressure is lower than that of the area surrounding it • Lows are associated with high winds, warm air, and atmospheric lifting. • Lows normally produce clouds, precipitation, and other bad weather such as tropical storms • Convergence of horizontal winds causes air to rise
Doppler Effect & Doppler Radar • Waves that bounce off moving objects are compressed • Meteorologists can determine which clouds are moving away and which are moving towards a given location
Downdrafts • Downdrafts are generated when rain-cooled, more dense air sinks inside a thunderstorm • Downdrafts rapidly transport precipitation out of the bottom of the cloud, and causes gusts of air to spread out from below the cloud. This is why it is often very windy before a thunderstorm arrives.
Drought • A drought is a period of unusually persistent dry weather that persists long enough to cause serious problems such as crop damage and/or water supply shortages. • Severity of the drought depends upon the degree of moisture deficiency, the duration, and the size and location of the affected area. • Current area of drought in U.S. • World-wide droughts
Flooding • A floodis an overflow of water that submerges land which is usually dry • Flash floods are usually the most lethal. • Slow onset floods, such as those that hit Bangladesh every year, can also be lethal but tend to give people much more time to move to higher ground.
Front Types • Cold front – cold dense air forces warm air upward forming intense rain clouds • Warm front – warm air advances over cold air forming widespread light precipitation • Stationary front – warm air and cold air masses meet but neither advances resulting in light wind and light rain • Occluded front – warm air is forced upward above 2 masses of cold air resulting in strong winds and precipitation
Frontal Wedging • Frontal wedging: warm air and cold air collide, since warm air is less dense it is wedged upward. This causes a front that's usually rain. Example: warm front
Gusty Surface Winds • Gusty surface winds can be produced by convection cells and thunderstorms
Hurricanes & Hurricane Formation • Hurricanes are characterized by high winds, heavy rain, flooding and a storm surge that arrives as winds push up offshore water levels
Hygrometer • hygrometer is a device for measuring the relative humidity of air • simple hygrometers use a human hair to expand and contract as humidity rises and falls
Jet Streams • Polar jet streams and subtropical jet streams are fast moving narrow bands of air in the stratosphere • Jet streams were discovered when jets traveling above the troposphere encountered 200 mph + winds • http://www.youtube.com/watch?v=CgMWwx7Cll4
Low Pressure vs. High Pressure Systems • Regions of sinking air are called highs, high pressure regionsor anticyclones. Clear skies and fair weather usually occur in these regions. • Regions of rising air are called lows, low pressure regions, depressions or cyclones. Clouds rain and strong winds often occur in these regions. • http://www.youtube.com/watch?v=aiYyCurh_SU
Mass Evacuation • Mass evacuation is recommended for hurricanes in order to prevent loss of life • Hurricanes can be predicted early enough to order an evacuation of an entire region in the path of a hurricane
Meteorology • Meteorology - The study of the atmosphere and all its phenomena, including weather and how to forecast it.
Reasons for the Seasons • Tilt of the Earth’s axis of rotation • Uneven heating of the Earth • Spherical shape of the Earth means equatorial region receives direct solar rays and other areas have sunlight spread out
Saffir-Simpson Hurricane Scale • The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 rating based on a hurricane's sustained wind speed. This scale estimates potential property damage.
Severe Weather & Seasonal Variations • Severe weather occurs at different locations at different times of the year • This is due to seasons
Severe Weather & Societal Impacts Drought Effects: • Loss of food production • Displacement as people move from affected area (Dust Bowl) Effects of Hurricane Katrina: • Unforeseen economic effects • Gas and Oil production shut-downs • Unemployment • Insurance Company Bankruptcies • Relocation/Flight from the region • Environmental Effects • Oil Spills • Erosion • Sewage • Loss of Marine and Animal life • Looting and Violence
Severe Weather Advisory Conditions exist that allow for the formation of: • Thunderstorms • Hurricane • Flooding • Blizzard conditions Advisories are issued if the weather event will lead to nuisance conditions • Warning/Advisory Indicates that a particular weather event is imminent or occurring. Advisories are issued if the weather event will lead to nuisance conditions, while Warnings are issued for significant weather events which will pose a risk to life and property. Warnings and Advisories are issued up to 48 hours in advance with forecaster confidence of at least 80%.
Severe Weather Types Worldwide • Tornado • Hurricane/Cyclone/Typhoon • Drought • Thunderstorms • Flooding • Blizzards • Ice storms • Hailstorms Are all forms of severe weather that occur in different locations and in different seasons
Severe Weather Warning Conditions currently happening • Thunderstorms • Hurricane • Flooding • Blizzard conditions Warningsare issued for significant weather events which will pose a risk to life and property. • Warning/Advisory Indicates that a particular weather event is imminent or occurring. Advisories are issued if the weather event will lead to nuisance conditions, while Warnings are issued for significant weather events which will pose a risk to life and property. Warnings and Advisories are issued up to 48 hours in advance with forecaster confidence of at least 80%.
Severe Weather Watch • WatchIndicates that conditions are favorable for the particular weather event in and near the Watch area, and which may pose a risk to life and property. Watches are issued up to 48 hours in advance with forecaster confidence around 50% Conditions exist that allow for the formation of: • Thunderstorms • Hurricane • Flooding • Blizzard conditions Weather Watch - conditions are favorable for the particular weather event in and near the Watch area, and which may pose a risk to life and property
Societal Impacts • Severe weather can affect: • food production • water resources • fishery abundance • public health • economy and jobs • For example, a drought may occur over a few months during a growing season, its adverse impacts on a society can linger for years. For example, a drought may occur over a few months during a growing season, its adverse impacts on a society can linger for years.
Storm Surge • Raised water levels that come ashore before a hurricane arrives • Most deaths and destruction are caused by flooding associated with storm surge
Thunderstorm • A thunderstorm is a storm with lightning and thunder. Its produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. All thunderstorms are dangerous. Every thunderstorm produces lightning. While lightning fatalities have decreased over the past 30 years, lightning continues to be one of the top three storm-related killers in the United States. In 2010 there were 29 fatalities and 182 injuries from lightning.
Tornado • A tornado is a narrow, violently rotating column of air that extends from the base of a thunderstorm to the ground. Because wind is invisible, it is hard to see a tornado unless it forms a condensation funnel made up of water droplets, dust and debris. What to do in a tornado:
Tornado Safety Measures • DURING A TORNADO: • Go to a basement. • If you do not have a basement, go to an interior room without windows on the lowest floor such as a bathroom or closet. • If you can, get under a sturdy piece of furniture, like a table. • If you live in a mobile home get out. They offer little protection against tornadoes. • Get out of automobiles. Do not try to outrun a tornado in your car, leave it immediately. • If you’re outside, go to a ditch or low lying area and lie flat in it. • Stay away from fallen power lines and stay out of damaged areas. http://www.weather.com/video/safest-place-during-tornado-35477
Updrafts • An upward current of warm, moist air. With enough moisture, the current may visibly condense into a cumulus or cumulonimbus cloud.
Weather • Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy.
Weather Maps p.355 • http://www.youtube.com/watch?v=aiYyCurh_SU • http://www.youtube.com/watch?v=ivSXkmL8ZbI&list=PL9FEF9BC1171615CA