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Atmosphere & Climate Change. Chapter 13, Section 1: Climate & Climate Change Standards: 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.
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Atmosphere & Climate Change Chapter 13, Section 1: Climate & Climate Change Standards: 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 Circulation Global 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 Circulation Prevailing 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.
