fronts and storms
DESCRIPTION
FRONTS AND STORMS. Weather Changes as air masses move. Forms when air sits for many days. Large volume of air. Covers thousands of miles. Air Mass. Same temperature and humidity in different locations. At the same altitude. Earth is cold. Air is cold. Earth is wet. Air is moist. - PowerPoint PPT PresentationTRANSCRIPT
FRONTS AND STORMS
Weather Changes as air masses move
Air Mass
Forms when air sits for many days Large volume
of air
Same temperature and humidity in different locations
At the same altitude
Covers thousands of miles
As air mass moves
Earth is cold
Air is cold
Earth is wet
Air is moist
It brings its Temperature and moisture to new location
Air masses are named according to the area where they form
First part of the Name:
Continental – means the air mass formed over land, air is dry
Maritime – means the air mass formed over water, air is moist
Second part of the name:
Tropical – means the air mass formed near the equator, air becomes warm, gains energy from land or water
Polar – means the air mass formed far from the equator, air becomes cool, loses energy to the cold land or water
How do air masses move ?
Air masses can travel away from regions where they form.
They move with the global pattern of winds. In most the United States, air masses generally move from west to east.
They may move along with the jet stream. In more complex and changing patterns
They bring their temperature and moisture to their new location.
Can cause weather to change
FRONTS
Boundary between air masses Clouds form Weather
becomes cloudy or stormy
Warm Front
Moves slow, brings many hours of rain or snow. After front passes air is warmer
Warm air moves up and over a mass of denser and colder air
Produces cloud covered skies high cirrus clouds
Symbol
Cold Front
Moves quickly, very steep
After front passes air is cooler and often very clear
Produces cumulonimbus clouds and precipitation
Brief, heavy storms are likely Cold dense air is moved
forward, warmer air is pushed upward
Symbol
Stationary Front
Symbol
Occurs when air masses meet, or when cold or warm fronts stop moving, boundary is in same locationClouds
cover the sky for days at a time
May become a warm or cold front, depends on which air is pushed down
High Pressure System
Large and change slowly
Water droplets evaporate, so clouds often disappear
Calm air or gentle breezes
Generally brings clear skies
Is formed when air moves all the way around a high pressure center
Low Pressure System
Air moves inward toward the low pressure and then up to higher altitudes
Is a large weather system that surrounds a center of low pressure
Air moves faster
Produces stormy weather
Northern hemisphere air circles in a counter clockwise direction
They often happen along the boundary of warm and cold air masses
Hurricanes
Warm water makes it bigger and stronger
Land or cool water makes them weak and lose energy
Tropical Low Pressure system
Winds blowing at speeds of at least 120Km/Hr.
Formed over the Indian Ocean or Western Pacific called Typhoons or Cyclones
Move westward with the trade winds
Strike b/w August and October
Low – Pressure Systems can become storms
FORMATION OF HURRICANES
Bands of heavy clouds and rain spiral inward toward
the eye
Center is called the EYE of the hurricane
The center is calm because the air moves downward
Air moves quickly around and upward
Tall ring of cumulonimbus clouds form the eye wall
The ring produces heavy rain and tremendous winds
EFFECTS OF HURRICANES
Strong winds
Heavy rain
May produce Tornadoes
Rivers may overflow and flood nearby areas
Can create a storm surge
STORM SURGE
Destructive and deadly
Huge mass of ocean water
Produces LARGE WAVES that can move back up
rivers and flood their shores
THUNDERSTORMS
ARE STORMS WITH
Lightning Thunder
VERTICAL AIR MOTION CAN CAUSE SEVERE STORMS
FORMATION OF THUNDERSTORMS
Rising humid air forms a cumulus cloud which eventually forms into cumulonimbus cloud
Ice particles form in the low T near the top of the cloud
The ice particles fall and pull cold air down
The downdraft created, produces heavy rain or hail
EFFECTS OF THUNDERSTORMS
Flash Floods
Strong Winds
Hail
Heavy Rain
Lightning
TORNADO
• Most common are small and last only a few minutes
• May lift dust and debris from the ground
• Violently rotating column of air
• Stretches from a cloud to the ground
• Moves along the ground in a winding path
• Column may rise off the ground and then come down in a different place
EFFECTS OF TORNADOES
Most common can pick up and slam dirt and small objects
Large tornadoes can knock over large trees
20% can lift cars off the ground
Tear roofs off houses
1% can lift or completely demolish sturdy buildings
METEOROLOGIST
Scientist who studies weather
Uses maps to display a lot of information at once
To predict weather they look at past and current conditions
Use technology to gather information
Weather forecasters use advanced Technologies
Fronts
WEATHER DATA
Isobars: Lines that connect places with the same air pressure. Isotherms: Lines of equal temperature.
Pressure systems
H L
B G Y R
Precipitation
FORECASTING
I. Is complicated
II. Short forecasts are the most accurate (3 days)
III. Fast changing weather is less accurate (storms)
COMPUTERS IN WEATHER
A. Important tool for forecasting weather
B.Scientists study the computer forecasts then apply
their knowledge and experience
C.Combine many types of data to forecast what might
happen next
D.Can create maps when weather stations send in data
GATHERING WEATHER INFORMATION
Ground Stations
Gathers data from just one place
Small area surrounding the station
Satellites
Gathers data from a large area
Surface of Earth below