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Transcript of Weather
An isolated storm contains multiple cells in different stages and last about an hour.
A large storm might be several tens of kilometers in diameter and can last many hours. This is a supercell thunderstorm.
A very tall cloud mass (cumulonimbus) with a flat and dark base.
Produces hail and/or rain.
Constantly changes (convection)
Three main parts: core region, spreading anvil top, and in-out flow region.
Huge! Hurricanes can grow to 600 miles across.
Spiraling winds can reach speeds of 75-200 mph.
Lasts for about a week.
Forms over tropical oceans.
Gathers heat and energy from warm ocean water.
Rotate counter-clockwise around an "eye" which is the calmest part of the storm.
Called typhoons in the Western Pacific.
Called cyclones in Australia and the Indian Ocean.
Technology for Measuring and Tracking
Satellite imagery tracks the movement of weather systems.
Computer model data helps identify where favorable areas for future storms are. Weather balloons are helpful in getting this data. Buoys are used in the ocean to monitor weather.
Aircraft and radar also help track thunderstorms.
Meteorologists issue a Severe Thunderstorm Watch when conditions are favorable, and a Severe Thunderstorm Warning when it has been sighted. These come from the National Weather Service.
Conditions for Formation
The atmosphere becomes unstable and forms large, powerful updrafts and downdrafts. This builds up a towering thundercloud. Sometimes the the updrafts
are very strong and push the top of the cloud into the tropopause which is the boundary between the troposphere and the stratosphere.
There has to be moisture in the atmosphere, middle level clouds, and heat or a low pressure trough.
Wind shear can extend the life of a thunderstorm.
Every thunderstorm is unique.
Hail 3/4 inch or greater, Wind gusts 58 mph or more, Can spin off a tornado
Thunderstorms come from cumulonimbus clouds.
Lightning is created by an electrical discharge because of positive and negative charges. Thunder is created by an explosion of noise from the sudden heating of atmospheric gases by lightning.
Thunderstorms are created from moisture, unstable air, and lift. They can occur year-round at any time of day but mostly occur in the spring and summer in the afternoon or evening.
Prepare an emergency pack
Move vehicles away from trees
Seek shelter indoors away from windows
Stay out of water (indoors and outdoors)
Avoid using a landline phone; don't use cordless or cell phone outside
Stay away from fallen trees, powerlines, and debris
Watch for flash flooding; seek highest level in your home
Keep children and pets inside until the storm has passed
Use a battery operated radio for storm updates
Technology to Measure and Track
Conditions for Formation
Ocean water must be 80 degrees Fahrenheit or warmer. The air has to cool quickly as it rises. The wind has to be blowing in the same direction at the same speed and force air up from the ocean. Bands of thunderstorms form and warms the air even more and rise higher into the atmosphere. If the winds at these higher levels are lighter the storm can remain intact and grow stronger creating a hurricane! Many hurricanes develop because of weather disturbances that are already happening in the area.
They usually form 5 to 15 degrees latitude north and south of the equator.
Geography Most Affected
Storm Surges cause Large Waves that crash into shorelines
Destruction to buildings, trees, and cars
Homes, Businesses, & Roads can destroyed
Technology for Measurement and Tracking
Scientists cannot yet precisely track and predict tornadoes. Meteorologists identify conditions likely to lead to severe storms.
Warnings are issued when atmospheric conditions are right for tornadoes to form.
Radar is used to track the path of thunderstorms that might produce tornadoes.
Storm spotters and storm trackers also play a key role.
Conditions for Formation
Geography Most Affected
Scale used for Measurement
What Are They?
Lake Effect Snow
Britannica Encyclopedia: www.britannica.com
YouTube: Hurricane Survival Video
Science Clarified: http://www.scienceclarified.com/Ti-Vi/Tornado.html
Weather Whiz Kids: http://www.weatherwizkids.com/weather-thunderstorms.htm
The Weather Channel: http://www.weather.com/encyclopedia/thunder/forecast.html
Australian Government Bureau of Meterology: http://www.bom.gov.au/storm_spotters/handbook/thunderstorms.shtm
Winter Storm: Blizzard
Atlantic hurricane season: June 1 - November 30.
Eastern Pacific hurricane season: May 15 - November 30.
Hurricanes occur most often in the Pacific Ocean, especially the Philippines.
Keep These Things In Mind:
Before a Storm:
Have an emergency plan ready
Know how to shelter your pets
Board up windows
Bring in outdoor objects that might blow away
Secure other outdoor objects
Know your evacuation routes
Prepare an emergency first aid kit
Prepare a disaster supply kit for your home and car that includes canned food and can opener, bottled water, battery-powered radio, extra batteries, flashlight, protective clothing
Make a checklist of things that need to be turned off in case of an emergency
Have necessary medicines refilled
Identify the weather update channel on your radio
Have extra cash in case banks and ATMS are closed after the storm
Fill your car with gasoline
During a Storm:
Stay away from low-lying and flood prone areas.
Stay indoors because strong winds will blow things around.
Leave mobile homes and to go to a shelter.
If your home isn’t on higher ground, go to a shelter.
If emergency managers say to evacuate, then do so immediately.
Ration out the items in your emergency kit.
Stay indoors until it is safe to come out.
Check for injured or trapped people, without putting yourself in danger.
Watch out for flooding which can happen after a severe storm.
Do not attempt to drive in flooding water.
Stay away from standing water. It may be electrically charged from underground or downed power lines.
Don’t drink tap water until officials say its safe to do so.
Replenish the items in your emergency packs that you used during the storm.
After a Storm
Hurricane Hunters with the National Oceanic and Atmospheric Administration (NOAA) fly through the storm with planes that carry radar, computers, and weather instruments to learn about the storms temperature, air pressure, wind speed, and wind direction. They also release instruments to measure temperature, air pressure, and wind at different levels as the devices drop through the hurricane.
Satellite images are used to follow and predict the formation and the path as well as the size of the hurricane.
Doppler Radar is used to detect rain associated with storms.
The U.S. Weather Bureau installed a national hurricane warning system.
Data Buoys are also used to help collect data on air and water temperature, wind speed, air pressure and wave conditions.
The Saffir-Simpson Hurricane Wind Scale: a 1 to 5 categorization based on the hurricane's intensity and provides examples of the damage and impacts in the United States associated with winds of the indicated intensity.
Rapidly spinning column of air formed in severe thunderstorms. Moves with the thunderstorm
The rotating column (vortex) forms inside the storm cloud and then grows downward until it touches the ground.
When a tornado is visible but does not touch the ground, it is called a funnel cloud.
A tornado in contact with a body of water is called a waterspout.
Very high wind speeds in a small area. (Average speed of 35 mph)
Average path length is 5 miles. Tornado diameters can very from 300 ft to 1 mile.
Vary in shape and size. Usually dark in color because of soil and other stuff picked up as it moves. Some have a funnel shape or a rope-like shape. Others have multiple vortices (many tornadoes around a common center). Some are hard to spot at all.
Funnel clouds are rotating cone-shaped columns of air extending downward from the base of a thunderstorm, but not touching the ground. When it reaches the ground it is called a tornado.
Each year around 80 deaths, 1,500 injuries, and millions of dollars of damage are caused by tornadoes in the U.S. Tornadoes:
Can shatter buildings, drive straws through solid wood, lift locomotives from their tracks, and pull the water out of small streams.
Can destroy large buildings, uproot trees, hurl vehicles hundreds of yards.
Damage paths can reach 1-50 miles long.
Can occur any time of the year but most are March-June
Thunderstorms grow in severity and spin off tornadoes
When updrafts in the storm get stronger air is pulled up into the base of the cloud and may being rotating.
When the air gets into a smaller area it rotates faster.
Meteorologists are still trying to discover if tornadoes form from deep within clouds and reach downward or if they form underneath and reach upward, or both.
The Fujita Scale is used to classify tornadoes and sometimes the damage done by other wind storms. The F-Scale uses numbers from 0 through 5, based on the amount and type of wind damage. The National Weather Service began using the scale in 1973, and also added the Pearson Scales to determine tornado path length and path width.
Get to a basement or an interior room without windows on the lowest floor (a bathroom or closet).
Get under something solid like a table.
Do not stay in a mobile home during a tornado.
Do not stay in your car or try to outrun the tornado.
If you are outside get into a ditch or low lying area and lie flat.
Stay away from fallen power lines.
If you are at school listen to your teacher and the overhead emergency announcements.
Get to an interior room or hallway on the lowest floor and crouch down on your knees and protect your head with your arms.
Most of the world's tornadoes occur in the United States (around 800 each year). The central part of the U.S., the Great Plains, has all of the ingredients a tornado needs to form. This area is known as "Tornado Alley" and includes Texas, Kansas, North Dakota, South Dakota, Oklahoma, Nebraska, Iowa, Missouri, Arkansas, Louisiana.
Winter storms get energy when two air masses with different temperatures and moisture levels collide. They usually form when cold and dry Canadian air moves south and meets a warm and moist air mass headed north from the Gulf of Mexico. Where these two masses meet is called a front. If the cold air moves forward and pushes past the warm air it is considered a cold front. If the warm air moves forward it goes over the more dense cold air and makes a warm front. When neither of the masses moves forward it creates a stationary front.
How do They Form?
are made of as many as 200 ice crystals and each snowflake has six sides. They form in clouds with below freezing temperature. Ice crystals form around tiny bits of dirt carried up into the atmosphere by wind They get heavier and heavier until they fall to the ground.
is formed when water vapor goes through deposition (changes straight to ice without becoming a liquid first) high in the atmosphere where the temperature is less than 32°F and then falls to the ground.
are snowstorms that last a long time and have strong winds and heavy snowfall. To have a blizzard there must be cold air at the surface, a lot of moisture, and lift. Warm air has to rise over cold air.
is when thunder and lighting occur during a snowstorm (most often in late winter or early spring). It starts like a summer thunderstorm with a mass of cold air on top of warm air, plus moist air closer to the ground. For thundersnow to occur, the air layer closer to the ground has to be warmer than the layers above, but still cold enough to create snow. There is heavy snowfall during thundersnow, sometimes two inches per hour.
is rain drops frozen into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. Sometimes it can accumulate like snow and become dangerous to drivers.
just rain that falls onto a surface with a temperature below freezing. This causes it to freeze to surfaces, such as trees, cars, and roads, forming a coating or glaze of ice. Even small buildups of ice can be dangerous.
is white ice crystals that form on a surface (the ground or leaves of a plant). Frost is created when the air temperature drops below freezing and the water vapor in the air freezes into ice crystals.
are caused by a sudden rapid freezing of ground and bedrock, usually when temperatures go from above freezing to below zero. When moisture and soil in the rock freezes and expands it can cause stress on the area around it and the soil and rock will crack. This "explosive" cracking creates a loud sound and can even shake the ground. Frost quakes usually happen over night when temperatures are colder.
Lake Effect Snow
occurs as cold air flows over warm lake water that heats the air's bottom layer. Since warm air is lighter than cold air, the heated air rises and begins to cool. As the air cools, the moisture that evaporated into it forms clouds which begins to drop snow.
occur in the eastern United States between October and April, when there is a lot of moisture and cold air. A Nor'easter is named for the winds that blow in from the northeast and drive the storm up the east coast along the Gulf Stream. They dump large amounts of rain and snow, produce hurricane-force winds, and create high surfs that lead to severe beach erosion and coastal flooding.
is an area of low pressure that forms over Alberta, Canada. Once an Alberta Clipper forms it moves very rapidly to the southeast across the U.S. northern Plains and then to the east off the mid-Atlantic Coast. They usually bring light precipitation and only a few cause major snowstorms. But some Alberta clippers can rapidly intensify off the East Coast once the storm reaches the relatively warm moist air over the Atlantic Ocean. The storms that rapidly intensify sometimes spread heavy snow over New England and southeastern Canada.
is caused by freezing rain. The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25-inch of ice on exposed surfaces.
Have a disaster plan and supply kit in your home and car.
Have a first aid kit, emergency food supply, bottled water, battery-operated radio, flashlight, protective clothing, and blankets.
Stay aware of the weather and weather changes.
Stay indoors and dress warm.
Eat regularly so your body can maintain energy to create heat.
Drink a lot of water.
If you go outside wear layered clothing, gloves, and head covering.
Watch for signs of frostbite or hypothermia.
Stay dry. Do not keep wet clothing on.
If you have to drive keep your cell phone with you. Make sure your gas tank is full.
Let someone know where you are going in case your car gets stuck.
If your car gets stuck, stay there unless you can see help within 100 yards. If you cannot see help do not try to walk in a winter storm.
Be careful if you are walking in heavy snow and beware of drifts covering ditches or holes.
After a snowstorm avoid overexertion- heart attacks from snow shoveling are a leading cause of death after winter storms.
Check on your neighbors.