1. Weather and Climate Study Guide

2. Weather Vs. Climate
Weather is the condition of the atmosphere at a certain time and place. The troposphere is where our weather takes place.
Climate is the average weather conditions in an area over a long period of time.

3. Unequal Heating
The source of all energy in our atmosphere that fuels Earth’s weather systems is the sun.

4. Unequal Heating Radiation – the heat energy that comes from the sun.
Not all radiation reaches Earth’s surface.
Some energy is absorbed by the atmosphere.
Some energy is reflected back into space.
Most energy is absorbed by the Earth’s surface.
Radiation balance – when the amount of energy received from the sun equals the amount of energy returned to space

6. There is unequal heating of the surface of the Earth.
a. The main reason for unequal heating is the Earth is curved, so not all areas receive the same amount of radiation. The sun’s rays strike Earth most directly at the equator, but at an angle as you go north or south. Therefore the equator is warmer than the poles.

8. Globe with Flashlight Demo.
1. Hold the flashlight a few inches from the globe aiming directly at the equator.
2. Hold the flashlight a few inches from the globe aiming at the poles.
*How does this show that the Poles will always be cooler than the Equator?

9. Land Vs. Water
b. Another reason for unequal heating is that land heats and cools faster than water because land absorbs the radiation from the sun faster than water.
Land/Water Demo.

10. Why does land win??
Only the surface of land absorbs heat (through conduction). This is faster. Water absorbs heat throughout (through convection). This takes much longer.

11. Air Pressure
There is a column of air above you at all times. The measure of the force with which air molecules push on a surface is air pressure, also called atmospheric pressure.

12. Air has mass, so it has weight.
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13. Air Pressure
B. There are 4 factors that influence the air pressure in an area:
Elevation
Temperature
Water Vapor
Location

14. Elevation
Air at sea level has more molecules in each cubic meter of space than air at the top of a mountain. The density of air decreases as altitude increases. Atmospheric pressure is greatest near Earth’s surface and decreases as you move upward away from sea level.

16. Molecules at Different Elevations

17. Air Pressure Tidbit Have you ever felt your ears “pop”?
People are not built for sudden air pressure changes.
As people go up, the outside pressure decreases. As people move down, the outside pressure increases.
Why do your ears pop as you go up or down in an airplane or a fast elevator? Air pressure inside and outside the middle ear normally is equal. But, as a person goes up, the outside pressure decreases, leaving the pressure inside the middle year higher. The air inside the ear usually moves through the Eustachian tube to the throat, equalizing the pressure. For instance, if a person has a cold, Eustachian tube might be blocked, making it harder for the air to leave the middle air and causing a sense of fullness or pain.

18. Temperature
The colder the air, the more the molecules move toward one another. Colder air is more dense. More dense air pushes down and has a higher air pressure than warm air. The warmer the air, the more the molecules move apart. Warmer air is less dense. Less dense air rises upward and has lower air pressure than colder air.

20. Water Vapor
More water vapor in air has less air pressure because part of the space is being taken up by water; therefore there are fewer air molecules per cubic meter of space available to push down. The most important function of the ocean is giving off water vapor into the atmosphere.

21. More water vapor=. Less water vapor= Less room for air molecules
More water vapor= Less water vapor= Less room for air molecules More room for air molecules

22. Location
Air closer to the poles is colder and more dense than air near the equator. Therefore there is more pressure near the poles than at the equator. Places that have similar latitudes (distance from equator) most likely have similar climates. Air moves in large, circular patterns called convection cells.

23. Air Pressure Clips https://www.youtube.com/watch?v=I0C4QR0 OEH0
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24. Wind
A. Differences in air pressure cause wind. Winds occur because air tends to move from regions of higher air pressure to regions of lower air pressure.
Remember the seven dwarfs?
“Hi-Low, Hi-Low, that’s how the wind blows!”

25. Wind 1. As warm air becomes less dense it rises. (low pressure)
2. The colder, more dense
air pushes down
(high pressure)
and rushes in to take
the rising, warm air’s place.

26. Wind 3. Winds are named from where they started or came from.
What winds are
prevailing over the
United States?

27. Local Winds
Local winds are temporary winds that blow in an area and are produced by temperature differences caused by local geographical features. Ex: Sea and Land breezes

28. Sea Breeze
a. Land heats up during the day b. Air over land gets warmer than air over water c. warm air over land rises, while cooler, more dense air from over water rushes in to take its place

29. Land Breeze a. Land cools down at night
b. Air over land gets cooler than air over
water
c. Warmer air over ocean rises while
cooler, more dense air from over land rushes in to take its place (Example: Before sunrise on the beach, air over water is warmer than air over land.)

30. Land Breeze
Observe an animation of land and sea breezes.

31. Global Winds
A. Global winds blow almost constantly in every direction. 1. Air above the poles is very cold (higher density and higher pressure). 2. Air above the equator is warmer (less density and lower pressure). 3. The lower pressure warm air rises and the higher pressure cold air sinks and rushes toward the lower pressure areas (equator). 4. The rising, low pressure air at the equator is pushed toward the poles creating global winds.

32. Global Wind Belts
global_wind_circulation.swf

33. Observe an animation of the Coriolis effect over Earth's surface.
5. Coriolis Effect – the rotation of the Earth causes the wind paths to curve to the left or right.
Observe an animation of the Coriolis effect over Earth's surface.
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34. Jet Stream
D. Jet stream - fast moving, narrow belt of wind that has a great impact on changing weather conditions because it determines major air movements.

36. Air Masses
Air mass - large body of air that gets its temperature and humidity from the land or water over which it forms The cause of changes in the weather is when air masses move and meet.