Download 8.10 A-C Weather Test Review! 8.10 A Convection Currents and the

8.10 A-C Weather Test Review!
8.10 A Convection Currents and the Sun’s Energy
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Convection is the transfer of heat in a liquid or a gas. Convection currents occur in Earth’s atmosphere
and in Earth’s oceans and are driven by solar energy (the Sun’s radiation creating heat).
Although the sun emits a constant amount of heat, the earth is unevenly heated by the sun. This is
due to the tilt of Earth on its axis. This uneven heating causes convection (without uneven heating,
we wouldn’t have convection!)
The Earth receives more solar energy at the equator, and is therefore warmer around the equator.
This is because the sunlight strikes the equator directly (90 degree angle, straight on). Earth’s poles
do not receive direct sunlight and are much colder as a result.
Convection currents in our atmosphere and oceans work in a similar way.
A. In the atmosphere, the sun strikes the earth’s surface, warming the ground. Air near the ground
heats up, expands and becomes less dense, and begins to rise. As it rises higher into the
atmosphere and gets farther away from the source of heat (the ground warmed by the sun), it
begins to cool off, contract and become denser, and begins to sink back down. Warm air rising
from the ground is replaced by cooler air. See below.
The sun warms the ground
Cool air is denser and sinks
Warm air is less dense and
rises
B. In the ocean, deep ocean currents are created by convection through differences in temperature
and salinity (amount of salt). The water near the poles is much colder and dense and sinks down.
Warmer, less dense water from the equator moves in to take the place of the water that is sinking.
See below.
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During the day, the Sun heats up the land more quickly than the ocean. (Oceans can absorb a lot of
heat before getting hot! …unlike land.) Air above water will be cooler. Warm air above the land rises.
Cool air above the ocean will rush in to take the place of the air that is rising. This creates wind
blowing from the ocean to the land! See pictures below.
8.10 B Weather Maps
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Know ALL of your weather map symbols, their names, and what kind of weather is associated with
them!
Cold front—
brings colder
temperatures
and often brings
thunderstorms
(can be severe)
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Warm front—
brings warmer
temperatures,
humidity, and
sometimes light
rain
Stationary
Front—light,
lasting rain with
little change in
temperature
High Pressure—
cool dense air
sinks bringing
dry, clear, sunny
skies
Low Pressure—
warm, moist air
rises bringing
cloudy, rainy
skies
Cold fronts are often associated with high pressure and warm fronts are associated with low pressure.
Air always moves from areas of high pressure (high density) to areas of low pressure (low density)!
Think about blowing up a balloon and letting it go. This creates wind.
Know weather tools names and what they measure:
o Anemometer (wind speed), Thermometer (temperature), Barometer (air pressure),
Hygrometer (humidity)
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Know how to read a weather map:
In front of cold front, warmer temperatures.
This cold front is headed east.
Along cold front, cooler temperatures and
thunderstorms
High pressure area, sunny and clear skies,
cooler temperatures
8.10 C Oceans and Weather
 Oceans absorb solar energy. Oceans absorb and release solar energy much slower than land. They
help keep our planet from getting way too hot during the day and way too cold at night.
 Ocean currents help regulate climate and weather! Ocean currents carry warm water from the
equator to areas closer to the poles, helping keep climate temperate (nice weather) all year round in
places like Ireland. Ocean currents can also carry cool water from the poles to areas closer to the
equator, helping keep climate temperate all year round in places like California.
 Hurricanes are complex weather systems that can include rain, winds up to 75 mph, bring storms,
usually form in the summer months, bring waves, and form in areas of low pressure.
o Hurricanes form over warm, tropical waters and are fueled by warm, moist air above the
ocean. As air evaporates from warm, moist ocean waters, it rises and creates a low pressure
area. A tropical depression forms as the warm, moist air rises, condenses, and begins to form
clouds and rain. Air continues to rush toward the area of low pressure creating a larger,
Tropical Storm. A hurricane forms when wind reaches 74mph +. Finally, a hurricane will “die”
when it reaches cold water or land. This is because it must have warm waters to form and
keep it going.
Other…
 Know your speed formula!