Weather
1. Atmosphere- the layer of gases that surrounds the planet.
a. Oxygen=21%
b. Nitrogen =78%
c. Other gases such as water vapor, carbon dioxide, helium, methane=1%
Earth’s atmosphere is made up of nitrogen, oxygen, carbon dioxide, water vapor, and many
other gases, as well as particles of liquids and solids
2. Air has pressure because it has mass. Dense, cool, air exerts more pressure than less dense
warm air. The result of weight of a column of air pushing down on an area. More pressure at
the bottom of a mountain than on the top.
3. A barometer is used to measure air pressure.
4. There are 4 main layers of the atmosphere that are classified according to changes in
temperature.
a. Troposphere- where weather occurs, layer that we live in.
b. Stratosphere- where you would find the ozone
c. Mesosphere- where meteoroids burn up
d. Thermosphere
5. The ozone layer absorbs ultraviolet radiation. 3 atoms of oxygen. It absorbs energy from the
sun; the energy is converted into heat, warming the air.
6. Heat is transferred by radiation conduction, and convection.
a. Radiation- direct transfer of energy by electromagnetic waves
b. Conduction- direct transfer of heat from one substance to another substance that it is
touching.
c. Convection- transfer of heat by the movement of a fluid (gas or liquid)
7. Winds are caused by a difference in air pressure. The difference in air pressure is caused by
unequal heating of earth’s surface.
8. Cold air masses tend to be more dense than a warm air mass, due to the molecules being
closer together. Since the cold air mass is more dense it tends to sink and go under a warm
air mass.
9. Local winds are caused by unequal hating of Earth’s surface within a small area.
Sea Breezes- a wind that blows from a lake or ocean onto land, this occurs in daytime due to
earth’s surface heating up more quickly.
Land Breezes- the flow of air from land to a body of water. This occurs at night because the
land tends to release it heat more quickly than the water.
Global winds- winds that blow steadily from specific directions over long distance. This is
created by unequal heating of Earth’s surface. They are trade winds, prevailing westerlies, and
polar easterlies.
10. Coriolis Effect- the way the earth’s rotation makes the wind curve. In the Northern hemisphere
the winds gradually turn toward the right and in the southern hemisphere the gradually curve
to the left.
11. Cumulus- looks like rounded piles of cotton. Means heap or mass, usually indicate fair
weather, they may grow in height.
Stratus- forms in flat layers usually covers the entire sky, may produce drizzle, rain, or snow,
they are low level clouds.
Cirrus- wispy, feathery clouds, form at high levels where temperatures are very low. Mostly
made up of ice crystals.
12. Maritime Tropical- warm, humid air masses form over oceans near the tropics. In the summer
it brings hot, humid weather. In the winter it can bring heavy rain or snow.
Maritime Polar- cool, humid air masses that form over the icy cold North Pacific and North
Atlantic oceans.
Continental Tropical- hot, dry air masses that form only in the summer over dry masses of the
southwest and northern Mexico.
Continental Polar- large polar air masses form over central and northern Canada and Alaska.
They bring cool and cold air. The air masses can form near the Arctic Circle and can bring
bitterly cold weather with very low humidity.
13. Thunderstorms form within large cumulonimbus clouds. They form on hot humid afternoons
in spring and summer.
14. Parts of a hurricane eye, which is the calm winds and the eye wall which is where the high
winds and storms come from.
15. Tornado Watch” - tornadoes possible in your area.
“Tornado Warning” - tornado has been seen in the sky or on a weather radar.
The safest place during a tornado is a basement of a well-built building. Move to the middle of
the ground floor.
Stay away from windows and doors.
Lie flat on the ground under sturdy furniture.
Move to a building or lie flat in a ditch
16. A meteorologist is someone who studies weather.
17. The reason why we have season is due to the fact that the earth is tilted. During the summer
the earth’s northern hemisphere is tilted toward the sun.
18. Climate refers to the average year after year conditions of temperature, precipitation, winds,
and clouds in an area.
19. Two main factors of determining the climate of a region is temperature and precipitation.