1. Weather and Climate Power Point

2. Atmospheric Composition
Our “air” is made up of:
78% Nitrogen
21% Oxygen
0-4% Water Vapor
0.93% Argon
.038% Carbon Dioxide
0.01% Trace Gases
(Carbon dioxide has increased from 0.028% over the past 150 years)

3. Layers of the Atmosphere:
Last/Outer Layer of our Atmosphere
Exosphere- the traditional boundary between Earth’s atmosphere and outer space.
Thermosphere: The layer has extremely low density which causes the temperature, temp is more than 1000°C.
This layer also contains the Aurora from solar wind!
Mesosphere: This layer actually decreases in temperature.
This is the layer that protects us from meteoroids!
Stratosphere- Here temperature increases with altitude, especially in the Ozone Layer. The UV absorption of UV radiation in the ozone causes the temperature to rise.
The OZONE layer protects humans from the extremely dangerous UV waves from the Sun.
Surface of Earth

4. Air Pressure is measured with a barometer.
Air Pressure is the weight of the air pressing down on you.
Air Pressure and Elevation- As you go higher in elevation, the air molecules are more spread out, therefore the air is less dense. Also, there is less air above you being pulled down on you by gravity.
Air pressure and Weather:
Sunny Weather= High Pressure (approx the weight of a school bus!)
Cloudy/Rainy Weather = Low Pressure (approx the weight of a Volkswagen beetle)
Why don’t humans crush if we are always under such extreme pressure?
Air Pressure is measured with a barometer.

5. Heat Transfers- The way heat is exchanged on Earth.
Radiation: The direct transfer of heat through the air.
Ex: sunlight, heat given off from a fire or stove
Conduction: The transfer of heat from one object to another.
Ex: heat from the hot pot to your hand
Convection: The circulation of heat through a liquid or gas.
Ex: Convection currents in the mantle or a boiling pot of water.
Why does warm air rise?

6. Rain but not thunderstorms
Cirrus tell that there will be a storm in a couple of days
These are the only vertical clouds and are the huge thunderstorm and tornado clouds.
Fair sunny weather
Rain but not thunderstorms
Cloud Formation- clouds form by tiny water droplets attaching to dust particles in the sky. Eventually the drops will build up on the dust until it becomes heavy enough for gravity to pull it to the Earth’s surface as precipitation.

7. The Water Cycle

8. ITCZ Low Pressure Intertropical Convergence Zone
Global Wind Systems:
Polar Easterlies
Prevailing Westerlies
Northern Trade Winds
ITCZ Low Pressure Intertropical Convergence Zone
Southern Trade Winds
Prevailing Westerlies
Polar Easterlies

9. Types of Precipitation
Rain- liquid precipitation
Sleet- frozen ice pellets (less than 5cm)
Freezing Rain- comes down as a liquid but freezes on contact leaving a glaze of ice.
Snow- frozen, six-sided crystals.
Hail- (only forms in cumulonimbus clouds) ice pellets that circulates vertically in the clouds and forms layers as it grows bigger.

10. Types of Air Masses
Air Mass- large volume of air that has characteristics of the area over which it forms.
A (Arctic)- Extremely cold and dry, forms over northern Canada.
cP (Continental Polar) dry and cold, forms over central Canada.
mP (Maritime Polar) Cold and wet, forms over northern Pacific and Atlantic oceans.
mT (Maritime Tropical) warm and wet, forms over southern Pacific and Atlantic Oceans.
cT (Continental Tropical) Warm and dry, forms over Mexico in the SUMMER ONLY.

11. Examples of Areas that have specific Air MassescP
cP- Central Canada, North Dakota, Siberia
mP- Maine, Northern Canadian Coast, Washington and Alaska
mT- Florida, Rainforests, Northern Australian Coast
cT- Texas, Mexico, Los Vegas, Arizona
A- Northern Siberia, Arctic Circle, Northern Canada and Alaska and Greenland mP mT mT cT A

12. Fronts- The boundary at the front of an air mass
The front created depends on the characteristics of the air mass..

13. Cumulonimbus Clouds- these are the dangerous thunderstorm clouds, they are also called thunderheads. These clouds usually form on a hot and humid day when the warm air rises quickly
Lightning- is a sudden spark or discharge released from energy within a cumulonimbus cloud. Lightning can be up to 30,000°C.
Thunder- is the sound of the explosion. Since light travels so much faster than sound, you always see the lightning first, than HEAR there explosion within seconds of the lightning.

14. Tornadoes- is a rapidly whirling, funnel-shaped cloud that reaches from the cloud to the Earth’s surface.
Tornadoes usually last less than 15 minutes but within that time, tornadoes can have winds speeds up to 320 miles per hour and be up to half a mile wide!
TV Warning vs Watch-
Thunderstorm or tornado Warning means that there IS A STORM or funnel cloud and it is heading your way!
Watch means that there is a very good chance that the thunderstorm and tornado COULD FORM.
Tornado Safety- safest places are a strong cement basement or bath tub with a mattress over your body. If in a car, get out! Get to a bridge overpass or lie in a ditch with your hands over your head away from any objects that could become projectile.

15. The Fujita Scale Rates Tornadoes :
Cause for Tornado Alley: 1. cP Air Mass from the north mixes with the mT from the south. The large temperature contrasts cause the formation of supercells (extremely powerful thunderstorms). The rotation begins within the thunderstorm clouds and the updrafts create a column which increases rotation. The air pressure lowers in the center causes a violent increase in wind speed.
The Fujita Scale Rates Tornadoes :
F0-F1 (last 1-10 minutes and winds up to mph)
F2-F3 (last 20 minutes, winds up to mph)
F4- F5 (Last up to 1 hour, winds are up to mph)
What is the most violent season for tornadoes?

16. Location of Tornado Alley

17. Hurricane Irene Hurricane Katrina Hurricanes: Hurricane Formation:
Warm air absorbs moisture from the ocean.
Water Vapor is lifted into the atmosphere.
As the water vapor rises, the cooler upper air condenses it into liquid droplets.
Condensation releases latent heat into the atmosphere, making the air less dense.
As the lighter air rises, moist air from the ocean takes its places creating a wind current.
Moving air begin the rotate due the Coriolis Effect (the process curving large wind and water systems due to the very fast rotation of the Earth)
Tropical Depression- Some thunderstorms and winds are mph
Tropical Storm- thunderstorm wall becomes more solid, winds 42-78mph
Hurricane or Cyclone- distinguished eye with a surrounding eyewall (layers of thunderstorms that surrounds the eye) and winds are more than 78 mph.
Hurricane Katrina

18. Climate- the average year after year conditions of temperature, precipitation, wind, and clouds of an area.

19. Tropical Moist Climates (Af) rainforest-Rainfall is heavy, more than 250 cm. (100 in.),temperatures of 27°C (80°F),Humidity is between 77 and 88%.
Wet-Dry Tropical Climates (Aw) savanna-there is a very wet season and a very dry season. It gets a little cooler during this dry season but will become very hot just before the wet season.
Dry Tropical Climate (BW) desert biome-These desert climates are found in low-latitude deserts approximately between 18° to 28°This makes for a very dry heat. The dry arid desert is a true desert climate, and covers 12 % of the Earth's land surface.
Moist Continental Climate (Cf) Deciduous Forest biome- This climate is in the polar front zone - the battleground of polar and tropical air masses. Seasonal changes between summer and winter are very large. Daily temperatures also change often. Abundant precipitation falls throughout the year.
Dry Midlatitude Climates (Bs) grasslands biome- Annual temperatures range widely. Summers are warm to hot, but winters are cold. These dry climates are limited to the interiors of North America and Eurasia.
Boreal forest Climate ( Dfc) taiga biome-This is a continental climate with long, very cold winters, and short, cool summers. Very cold air masses from the arctic often move in.
Tundra Climate (E) tundra biome- Polar and arctic air , The winter season is long and severe, A short, mild season exists, but not a true summer season, technically a desert due to very little precipitation
Highland Climate (H) Alpine Biome- Highland climates are cool to cold, found in mountains and high plateaus. Climates change rapidly on mountains, becoming colder the higher the altitude gets. The climate of a highland area is closely related to the climate of the surrounding biome.
Marine Biome- All fresh and saltwater ecosystems.