Download NEW Common Weather Exam Study Guide Highlights 2012-2013

Grade 6 Science Final Review
Weather Section: Highlights of What We Learned
Things to Know:
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The atmosphere is an ocean of air that surrounds the Earth. The atmosphere is composed of
several layers including:
E......
Exosphere- last layer of atmosphere, almost deep space, almost perfect vacuum
Is
Ionosphere- bounces radio waves back to Earth
Making
Mesosphere- a middle layer that marks the end of the lower atmosphere and the
beginning of the upper atmosphere, meteors burn up here
Some
Stratosphere- 10- 30 miles high, contains the ozone layer. The ozone layer
protects Earth from ultraviolet radiation.
Toast
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Troposphere- layer closest to Earth, where we live and where weather occurs
The atmosphere is a mixture of gases; it contains about 78 per cent nitrogen and 20 per
cent oxygen. The atmosphere is important as it provides all the gases living things need.
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Normal air pressure, the weight of the atmosphere, at sea level is 14.7 pounds per square
inch. As you rise in altitude air pressure decreases.
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A barometer is an instrument used to measure air pressure. A rising barometer indicates
dry, pleasant weather. HIGH= DRY
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Heat from the sun reaches you by radiation. This energy from the Sun comes to Earth in
different types:
Visible Light: The colors you see
Infrared Radiation: Felt as heat
Ultraviolet Radiation: Can cause sunburns and also skin cancer
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The process where gases trap heat in the atmosphere is known as the Greenhouse Effect.
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Weather is the condition of the atmosphere at any time. The factors that make up
weather are temperature, air pressure, moisture in the air (humidity), clouds, precipitation
(rain or snow), wind speed and direction.
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In Celsius the freezing point is 0 degrees, the boiling point in 100 degrees.
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In Fahrenheit the freezing point is 32 degrees, the boiling point is 212 degrees.
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The weather conditions over a long period of time for any location are known as climate.
Climate is the average conditions of temperature, precipitation, winds, and clouds in an area.
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There are three major climate zones. Near the equator, between 0 and 30 degrees
latitude is the tropical zone (warmest). Further from the equator, between 30 and 60
degree latitude is the temperate zone (medium temperatures). Near the North and
South Poles, between 60 and 90 degree latitude is the polar zones (coldest). The
continental United States is located in the temperate zone.
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In the United States the main flow of air (wind) is west to east. The Jet Stream is a
powerful wind in the upper atmosphere that blows west to east.
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Winds are caused by differences in air pressure. Local winds blow over short distances,
global winds blow from specific directions over long distances. The Carioles effect causes
global winds to curve due to Earth’s rotation.
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The water cycle includes evaporation (liquid to gas), condensation (gas to liquid), and
precipitation (rain or snow). The Sun provides energy for the water cycle.
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The weather over the United States is caused by six major air masses, huge masses of air
with certain characteristics. They include:
Maritime Polar- cool, wet
Maritime Tropical- warm, wet (affects weather in Florida)
Continental Polar- cool, dry
Continental Tropical- warm, dry
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During the day, warm air rises over the land, and cool air blows in from the ocean. This is
called a sea breeze. At night, the land cools off first, warm air rises over the ocean, and
cool air blows from the land towards the water. This is called a land breeze.
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There are three main types of clouds: (clouds form when water vapor condenses onto dust)
Cirrus- very high, feathery "horse tails", appear during fair weather but indicate
a change to stormy weather in 24 to 48 hours.
Cumulus- white puffy clouds, usually indicate fair weather
Stratus- flat clouds that cover the sky, usually indicate stormy weather
Cumulonimbus- Dark clouds that produce thunderstorms.
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Hurricanes are huge tropical storms that begin over warm oceans. The center of a hurricane,
called the eye, is usually calm. A storm surge occurs when water sweeps across the coast
where a hurricane lands.
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Tornadoes are concentrated whirling winds where funnel shaped clouds reach the Earth.
Tornados occur over land, most in "Tornado Alley" (TKO= Texas, Kansas, Oklahoma)
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Blizzards are winter wind and snowstorms.
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The boundary between weather systems is called a front.
Cold Front- Cold air overtakes warm.
Warm Front- Warm air overtakes cold.
Stationary Front- Dos not move.
Occluded Front•
Humidity is the amount of moisture in the air. It is measured by a percent, and is called
relative humidity. A psychrometer is used to measure humidity.
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Cold air holds less water, warm air holds more water. When the air becomes saturated
(full of moisture) at a certain temperature, the water vapor condenses to a liquid. Above
freezing, this is called dew. Below freezing, it is frost.
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Cold air is denser, while warm air is less dense.
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Important weather instruments include:
Thermometer- measures air temperature
Anemometer- measure wind speed
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Wind Vane- indicates wind direction
Rain gauge- measures amount of precipitation
An isobar is a line on a weather map that connects cities with the same air pressure.
Isotherms connect places with the same temperature.
Good Weather- Low humidity, Small puffy cumulus clouds, rising or high
barometer readings.
Stormy Weather- High Humidity, Low dark stratus clouds, falling or low
barometer readings.
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As you get further from the equator (change latitude), the temperature gets cooler. The
sun's rays are most direct at the equator.
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The windward side of a mountain generally has a wet climate. The leeward side generally
has a dryer climate.
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