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.