Weather and Climate Study Guide
1.
Water Cycle: the continuous process by which water is used and re-used on earth; responsible
for weather and climate.
a. Evaporation: when a liquid (water) is changed to a gas (water vapor) because it has been
heated by the sun
b. Condensation: when a gas (water vapor) changes to a liquid (water droplets) because it has
been cooled
i. This process forms clouds.
c. Precipitation: rain, sleet, snow, or ice that falls from the sky to earth; happens when the
clouds become too full or heavy; measured with a rain gauge
2.
Weather: the state of the atmosphere at a given time; the short-term conditions, such as
temperature, precipitation, wind, humidity, and air pressure.
3. Climate: the pattern of weather over a long period of time (the average weather conditions,
usually over many years)
a. Climate is affected by temperature, precipitation, latitude, wind, ocean currents, and the
shape of the land (mountains)
4. Humidity: the amount of water in the air; measured by a hygrometer
5. Temperature: measured by a thermometer
6. Air pressure: the weight of the atmosphere; measured by a barometer
a. High pressure: cool, dry conditions (clear skies)
b. Low pressure: warm, wet conditions (stormy or rainy)
7. Wind: caused by changes in temperature; moves from areas of high pressure to areas of low
pressure; wind speed is measured by an anemometer; wind direction is measured by a wind vane.
8.
Prevailing winds: winds that constantly blow from the same direction.
a. Our prevailing winds are known as the “prevailing westerlies” (always blow from west to
east)
9. Sea Breeze: winds that blow from the sea toward the land; happens during the daytime when the
air is cooler over the water and warmer over the land.
10. Land Breeze: winds that blow from the land toward the sea; happens during the nighttime when
the air is cooler over the land and warmer over the sea.
11. Cumulus clouds: large, puffy clouds that look like cotton balls or cotton candy
a. Name means “heap”
b. Usually mean fair weather, but can bring rain
c. Usually white in color
12. Cirrus
a.
b.
c.
d.
clouds: thin, wispy clouds that form high in the sky
May contain ice crystals
Usually white in color
Associated with fair weather and high pressure
Name means “curl of hair”
13. Stratus clouds: low, flat clouds that form in layers
a. Cause fog to form
b. Usually gray in color
c. Typically associated with rain or snow
d. Cover the sky like a blanket
14. Nimbus clouds: rain clouds
15. Cumulonimbus clouds: very tall clouds which produce stormy weather
a. Usually gray or black in color
b. Very tall
c. Also known as “thunderheads”
16. Tropical Climate Zone: found near the equator; hot year-round; heavy precipitation
a. Aligns with the tropical rain forest biome
17. Temperate Climate Zone: cold winters, warm summers, moderate precipitation
a. This is the climate zone in which we live.
18. Desert Climate Zone: hot summers, cool winters, light precipitation
a. Aligns with the desert biome.
19. Mountain Climate Zone: cold winters, cool summers, moderate to heavy precipitation
20. Polar Climate Zone: cold year-round; light precipitation
a. Aligns with the tundra and taiga biomes.
21. El Nino: a short-term climate change which happens as a result of changing ocean currents;
happens every 2 to 10 years.
22. Greenhouse Effect: when carbon dioxide in the atmosphere absorbs some of earth’s heat
a. The greenhouse effect is necessary for life on earth.
b. Carbon dioxide is added to the atmosphere by the burning of fossil fuels.
23. Global Warming: a gradual warming of earth’s climate over time, due to increased carbon
dioxide in the atmosphere (again, through the burning of fossil fuels)
24. Urbanization: a trend in which urban areas (cities) are several degrees warmer than surrounding
rural areas (country).
a. Tall buildings prevent winds from blowing through.
b. Cars, trucks, and buses give off exhaust.
c. Sidewalks and roads hold heat more than trees and grassy areas.
Additional Information:
 All weather occurs in the atmosphere. Most weather occurs in the lowest layer of the
atmosphere, called the troposphere.
 Land heats up faster than water, and also cools down faster than water.
 Most evaporation occurs over oceans.
 Clouds forms when water vapor condenses into water droplets. These water droplets combine
with dust in the atmosphere to form visible clouds.
 When warm air and cool air collide, wind forms. Warm air rises. As it rises high into the
atmosphere, it begins to cool, which therefore causes it to sink.
 Mountains affect temperature and precipitation.
 Places near large bodies of water, like oceans and lakes, will be milder than areas at the same
latitude.
WEATHER INSTRUMENTS
thermometer - an instrument used to measure air temperature
barometer - an instrument used to measure air pressure
rain gauge - an instrument used to measure the amount of precipitation
anemometer - an instrument that measures wind speed
wind vane – shows direction of wind
hygrometer – measures humidity or water in the air
AIR MASSES AND FRONTS
An air mass is a large body of air with about the same temperature and humidity throughout.
A front is where two different air masses meet. In the United States they usually move west to east.
At a cold front, a cold air mass bumps against a warm air mass and strong storms happen.
At a warm front, a warm air mass meets a colder air mass and slowly rises over it. Stratus clouds form
at warm fronts. They often bring rain. After a warm front passes, the temperature of the area rises.
A stationary front forms when two air masses meet and stop moving. Stationary fronts bring clouds and
precipitation, sometimes lasting for several days.
GLOBAL WEATHER PATTERNS
A jet stream is an air current in the upper atmosphere that moves west to east and greatly affects our
weather.
The Gulf Stream is a warm ocean current in the Atlantic Ocean. It helps keep weather along the eastern
coast of the U.S. milder by warmimg the air and land there during the cooler months.