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Atmosphere & Climate ChangeChapter 13, Section 1: Climate & Climate ChangeStandards: SCSh2a,b, 3c, 4a, 6a, d
What is the difference between weather & climate? Weather is the state of the
atmosphere at a particular place at a particular moment. Ex: it is raining outside
today. Climate is the long-term
prevailing weather conditions at a particular place based upon records taken. Ex: it is hot and humid in
the southeast during the summer months.
What factors determine climate? Latitude Atmospheric
circulation patterns Oceanic circulation
patterns Local geography Miscellaneous
Solar activity Volcanic activity
Latitude Distance from the equator measured
in degrees north or south. Low latitudes: near the equator (0°)
and about 30° above and below. Gets most sunlight, night & day are
about 12 hrs each, temperatures are high year round and no summers or winters
High latitude: from about 30° latitude to the north & south pole (90°). Gets less sunlight, night & day vary
during summer & winter, Summer- 12 hrs daylight in our area;
2-4 hrs of nighttime at poles Winter- 8 hrs daylight in our area; 24
hrs; 2-4 hrs of daylight at poles.
Atmospheric Circulation 3 important properties of air:
Cold air sinks, compresses, and warms b/c it is denser than hot air.
Warm air rises, expands, and cools as it rises.
Warm air can hold more water vapor than cold air. As warm air cools it condenses
and makes rain The rotation of these 3
properties creates wind. Uneven heating of Earth & Earth
spinning alter the movement of wind on Earth and create wind patterns.
Atmospheric CirculationGlobal Circulation Patterns At equator, cool air cannot sink
due to all the warm air rising up. This cool air is forced away from
the equator & moves toward the poles.
At about 30° N and S of equator, the cool sinks
The cool air starts to warm and sucks moisture from ground below.
This is what creates deserts at 30° N & S latitude.
Same basic process happens at 60° latitude.
Atmospheric CirculationPrevailing Winds Winds blow predominantly in one
direction throughout the year. Because Earth rotates, these
winds do not blow directly north or south- instead they are deflected
Wind patterns in Northern Hemisphere: Tradewinds- btwn 0-30° latitude;
blow from the NE Westerlies- btwn 30-60° latitude;
blow from the SW Easterlies- btwn 60°-poles; blow
from the NE parts of poles
Air circulation pattern animation
Ocean circulation patterns Have large effect on
climate because water holds lots of heat.
Movement of ocean water caused by Winds Earth’s rotation
Moving ocean water redistributes warm and cold surface water
Can have an effect on local coastal climates.
El Nino Southern Oscillation (ENSO)
El Nino Change in warm & cold
water masses in Pacific ocean
Pacific winds strengthen and push warm air & rain toward southern US & South America. Makes it drier in Australia & Indonesia
La Nina Opposite of El Nino… water
is cooler than normal. Both can alter fishing
industry in S. America. El Niño-Southern Oscillation - YouTube
Topography Height above sea level
influences climate. Temperatures fall 11°F for
every ½ mile increase in elevation.
Rain shadow effect As air moves east toward
Rocky mtns, the height of the Rockies block the weather. Rain falls on the western side of the mountain making the eastern side drier.
Miscellaneous Influences Solar Activity
Solar maximum- sun emits an increased amount of UV radiation, warming the surface of the earth a little
Volcanic Activity Produce sulfur dioxide
that can react with dust & water vapor to make haze that reflects light and cools global temperatures
What causes our seasonal changes? Caused by tilt of
Earth’s axis. Angle at which the
sun’s rays strike the Earth changes as the Earth moves around the sun.
You should be able to: Explain the difference between weather
and climate. Name four factors that determine
climate. Explain why different parts of the Earth
have different climates Explain what causes the seasons.