1. The Earths Weather

2. Layers of the Atmosphere  The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space.atmosphere  The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space.atmosphere

3. Layers of the Atmosphere  Troposphere - This is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer TroposphereWeather  Stratosphere - Many jet aircrafts fly in this layer because it is very stable. Also, the ozone layer absorbs harmful rays from the sun.  Mesosphere - Meteors or rock fragments burn up in this portion of the atmosphere  Thermosphere - This is the layer with auroras. It is also where the space shuttle orbits. Thermosphere  Exosphere - This is the area where the atmosphere merges into space, this area is extremely thin. It is the upper limit of our atmosphere. Exosphere  Troposphere - This is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer TroposphereWeather  Stratosphere - Many jet aircrafts fly in this layer because it is very stable. Also, the ozone layer absorbs harmful rays from the sun.  Mesosphere - Meteors or rock fragments burn up in this portion of the atmosphere  Thermosphere - This is the layer with auroras. It is also where the space shuttle orbits. Thermosphere  Exosphere - This is the area where the atmosphere merges into space, this area is extremely thin. It is the upper limit of our atmosphere. Exosphere

5. Explanations of Weather  Scientific explanations of weather phenomena primarily involve principles of: –heat transfer  Convection  Conduction  Radiation –energy transformations  production of thunder and lightning –changes or state within the water cycle  Precipitation  Evaporation  Scientific explanations of weather phenomena primarily involve principles of: –heat transfer  Convection  Conduction  Radiation –energy transformations  production of thunder and lightning –changes or state within the water cycle  Precipitation  Evaporation

6. Weather  As a result of these principles interacting, hot, cold, warm, and cool air masses develop.  They are usually very large and can cover several states in the United States.  These air masses develop as the air lingers in the same places for several days or weeks.  The air masses become dry or humid matching the surface below.  There are four air masses that affect the weather of the United States.  As a result of these principles interacting, hot, cold, warm, and cool air masses develop.  They are usually very large and can cover several states in the United States.  These air masses develop as the air lingers in the same places for several days or weeks.  The air masses become dry or humid matching the surface below.  There are four air masses that affect the weather of the United States.

7. Air masses  1) Continental polar air mass –over Northern Canada and Alaska  2) Maritime polar air mass –over North Pacific Ocean  3) Maritime tropical air mass –over the Gulf of Mexico and Caribbean  4) Continental air mass –over the southwestern states and Mexico  1) Continental polar air mass –over Northern Canada and Alaska  2) Maritime polar air mass –over North Pacific Ocean  3) Maritime tropical air mass –over the Gulf of Mexico and Caribbean  4) Continental air mass –over the southwestern states and Mexico

8. Air Masses

9. Air and pressure  Air is moving molecules of gas.  These gas molecules are constantly moving and pushing on each other and anything in their way.  This pushing power is called air pressure.  Air is moving molecules of gas.  These gas molecules are constantly moving and pushing on each other and anything in their way.  This pushing power is called air pressure.

10. Air pressure  Air pressure can change depending on how many molecules are in a given space and how fast they are moving.  The more molecules in a given space and the faster the molecules move, the greater the air pressure.  If air molecules are heated in a confined space, the pressure increases.  If the space is decreased for the same amount of molecules, the pressure will rise.  Air pressure can change depending on how many molecules are in a given space and how fast they are moving.  The more molecules in a given space and the faster the molecules move, the greater the air pressure.  If air molecules are heated in a confined space, the pressure increases.  If the space is decreased for the same amount of molecules, the pressure will rise.

11. Types of pressure  The uneven heating of the earth results in uneven air pressure on the earth  On a weather map –"H" marks areas that have high pressure  High pressure areas are generally correlated to clear skies  High pressure prevents water vapor from rising to form clouds –"L" marks the low pressure areas  low pressure areas produce clouds and precipitation  The uneven heating of the earth results in uneven air pressure on the earth  On a weather map –"H" marks areas that have high pressure  High pressure areas are generally correlated to clear skies  High pressure prevents water vapor from rising to form clouds –"L" marks the low pressure areas  low pressure areas produce clouds and precipitation

12. Wind  Wind –Produced as air moves from high pressure to low pressure areas  The closer the high and low pressure areas are to each other, the stronger the winds –Winds in a high pressure area  move clockwise –Winds in a lower pressure area  move counter-clockwise  Wind –Produced as air moves from high pressure to low pressure areas  The closer the high and low pressure areas are to each other, the stronger the winds –Winds in a high pressure area  move clockwise –Winds in a lower pressure area  move counter-clockwise

13. Weather Fronts  When air masses meet – a front develops – at fronts where cold and warm air meet, we get  violent storms  bad weather –winds bring in air to equalize the pressure when a high pressure collides with a low pressure area  When air masses meet – a front develops – at fronts where cold and warm air meet, we get  violent storms  bad weather –winds bring in air to equalize the pressure when a high pressure collides with a low pressure area

14. Types of fronts  1) warm front –warm air replacing cold air –the lighter warm air slips over the heavier cold air forming a gradual slope –clouds increase and become lower (drop in height)  1) warm front –warm air replacing cold air –the lighter warm air slips over the heavier cold air forming a gradual slope –clouds increase and become lower (drop in height)

15. Types of fronts  2) Cold front –cold air displaces the warm air –the heavier cold air shoves under the lighter warm air  pushes the warm air up very fast carrying moisture with it  clouds form  the steep slope between these two air masses  2) Cold front –cold air displaces the warm air –the heavier cold air shoves under the lighter warm air  pushes the warm air up very fast carrying moisture with it  clouds form  the steep slope between these two air masses

16. Types of fronts  3) stationary front –neither the cold or warm air is advancing  3) stationary front –neither the cold or warm air is advancing

17. CAUSES of LIGHTNING AND THUNDER  Lightning heats air molecules to 54,000 degrees F –This causes the surrounding molecules to explode outward –They come back again as static electricity  caused by the moving of water molecules in the clouds  Thunder is the sound that is made by air molecules when lightning strikes through the atmosphere –results from the rapid heating and expansion of air by lightning –causes a "shock wave" in the air  Lightning heats air molecules to 54,000 degrees F –This causes the surrounding molecules to explode outward –They come back again as static electricity  caused by the moving of water molecules in the clouds  Thunder is the sound that is made by air molecules when lightning strikes through the atmosphere –results from the rapid heating and expansion of air by lightning –causes a "shock wave" in the air

18. Reading Weather  Humans can use technology to predict the weather –thermometers - temperature readings –barometers - air pressure –hygrometer - relative humidity –wind vanes - direction of wind –anemometer - speed of wind –Beaufort Wind Scale - spread of wind –rain gauge - amount of rainfall –weather satellites, weather planes, weather balloons, and radar - are used for measuring many weather components  Humans can use technology to predict the weather –thermometers - temperature readings –barometers - air pressure –hygrometer - relative humidity –wind vanes - direction of wind –anemometer - speed of wind –Beaufort Wind Scale - spread of wind –rain gauge - amount of rainfall –weather satellites, weather planes, weather balloons, and radar - are used for measuring many weather components