What is Climate?

Climate is the average weather conditions of a specific region over a long time, (tens to thousands of years) including the range of weather conditions (variables).

What are the Variables of Weather?

1) Temperature 2) Air Pressure 3) Humidity

(moisture content)

4) Wind 5) Cloud Cover 6) Precipitation 7) Storms

Climate is Based on

The Water Cycle

Factors that Affect Climate

1. Latitude

2. Altitude (elevation)

3. Proximity to Large Bodies of Water

4. Ocean Currents

5. Mountain Barriers

6. Prevailing Winds

Latitude

The duration of insolation at low latitude is pretty much constant, temperature variance is small. The angle of insolation is always quite high. Therfore, the temperature is high as well.

At high altitudes, temperatures vary but remain relatively low because of the generally low angle of insolation.

Lines of Latitude

Important to Remember As the duration of

insolation increases, so does the temperature. As latitude increases, the average yearly temperature decreases but annual temperature range increases.

Lines of Latitude

Elevation

The elevation, (altitude) affects the moisture and temperature patterns of a region. The effects of elevation are similar to latitude.

Lower elevations are more stable in temperature and moisture while high elevations have more variation.

As altitude increases the average yearly temperature decreases and the precipitation generally increases.

Altitude and Elevation

Large Bodies of Water

Refer to the following website:

http://www.uwmc.uwc.edu/geography/100/koppen_web/koppen_map.htm

Large bodies of water (large lakes and oceans), ocean currents, and prevailing winds modify the latitudinal climate patterns of their shoreline areas.

Large Bodies of Water (continued)

The slow heating and cooling of large bodies of water cause the land masses near them to have modified temperatures.

Can anyone tell us why?

Large Bodies of Water (continued)

Maritime Climate

Areas on the North (West & East) coast of the US are characterized by cooler summers and warmer winters than would normally be expected for that latitude.

Areas of maritime climate have small temperature ranges.

Large Bodies of Water (continued)

Continental Climate

Inland regions (not surrounded by water) are not directly affected by large bodies of water. They have continental climates. These climates are characterized by hot summers and cold winters.

Ocean Currents (p. 4 of your reference table)

Ocean Currents

Maps of global winds and ocean currents look similar. This is because the winds blowing over the water create a frictional drag resulting in surface currents.

The Coriolis effect (caused by earth’s rotation) results in surface currents being deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Ocean Currents

Surface currents may either be warm or cold depending upon the temperature of the water through which they are passing and their direction.

Warm currents flow away from the equator and cold currents flow towards the equator. (Please write this on p. 4 of your reference table)

Ocean Currents

As warm water flows away from the equator it helps to distribute the solar energy it has absorbed from the low latitudes to the higher latitudes.

Land closer to warm ocean currents tend to be warmer than would be expected at that latitude. Cold ocean currents have the effect of making nearby land cooler than would normally be expected.

Mountain (Orographic Barriers)

The overall effect on climate patterns is called the orographic effect.

The latitudinal climate patterns are modified by mountains that act as barriers to local weather systems by interrupting the normal path of a prevailing wind.

Mountain (Orographic Barriers)

The windward side, is the side facing the prevailing wind. As the wind hits the windward side of the mountain the air is forced upward and cools by expansion until the dew point is reached.

Condensation then occurs and cooling slows. These conditions cause the water in the air to condense forming clouds and precipitation on the windward side.

Mountain (Orographic Barriers)

The leeward side, will be drier and warmer than the windward side. It is said to be in the rain shadow.

As the air rises over the mountain and begins to descend on the leeward side, it warms because of the compression increasing its ability to hold moisture.

What do we see in the orographic effect?

Windward Side (the side that receives the wind)

1. Moist Air Rises

2. Air Expands

3. Air is Cooled

4. Moist Air Condenses and forms clouds.

Leeward Side (the side that does not receive the wind)

1. Dry Air Sinks

2. Air is Compressed

3. Air is Warmed

4. Air is very dry (the rain shadow effect)

The Orographic Effect (The Mountain Effect)

Prevailing Winds

The planetary winds and pressure belts affect moisture and temperature patterns.

If the prevailing wind first crosses a large body of water before coming on land, it will bring moisture to the land.

If the prevailing wind crosses a large land mass, the effect would be arid (dry).

Prevailing Winds

Prevailing Winds from the tropics (equator) including warm ocean currents, will bring warm moist air.

Prevailing Winds from the polar regions (north and south) will bring cool dry air.

What is an El Niño an La Nina??

El Niño is characterized by unusually warm ocean temperatures in the Equatorial Pacific, as opposed to La Niña, which characterized by unusually cold ocean temperatures in the Equatorial Pacific. El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.

What are El Nino and La Nina?

El Nino - (El Nee-nyo) is the warming of water in the Pacific Ocean.

La Nina - (Lah Nee-Nyah) is the cooling of water in the Pacific Ocean.

Comparison of El Nino to La NinaEl Nino Weather Rain and flooding along

the Pacific coast Warm water disrupts

food chain of fish, birds, and sea mammals

Tornadoes and thunderstorms in southern US

Fewer than normal hurricanes in the Atlantic

La Nina Weather Snow and rain on the

west coast Unusually cold weather

in Alaska Unusually warm weather

in the rest of the USA Drought in the southwest Higher than normal

number of hurricanes in the Atlantic

How does El Nino and La Nina Form?

  http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.html

Interesting Facts

El Nino was first discovered hundreds of years ago by fishermen off the coast of Peru.

El Nino means "Little Boy" and was named after the Christ child, because it usually starts around Christmas.

El Nino is officially called ENSO - El Nino Southern Oscillation. La Nina means "Little Girl." It is also called El Viejo, which

means "old man," or an ENSO cold event. La Nina occurs roughly half as often as El Nino El Nino and La Nina are the most powerful phenomenon on the

earth and alter the climate across more than half the planet. El Nino may be caused by underwater volcanoes in the Pacific.

Years of El Nino

1902-1903 1905-1906 1911-1912 1914-1915

1918-1919 1923-1924 1925-1926 1930-1931

1932-1933 1939-1940 1941-1942 1951-1952

1953-1954 1957-1958 1965-1966 1969-1970

1972-1973 1976-1977 1982-1983 1986-1987

1991-1992 1994-1995 1997-1998 ?????????

Years of La Nina

1904-1905 1909-1910 1910-1911 1915-1916

1917-1918 1924-1925 1928-1929 1938-1939

1950-1951 1955-1956 1956-1957 1964-1965

1970-1971 1971-1972 1973-1974 1975-1976

1988-1989 1995-1996 1998-1999 ????

Koppen Climate Zones

Lab Activity #10: Climates of an Imaginary Continent

Please complete lab activity #10: Climates of an Imaginary Continent.

An Imaginary Continent

HW #10, July 26, 2010

Please read pages 160-163. make a summary on the factors that affect infiltration and the factors that affect runoff and stream discharge.

For homework tonight please complete questions 26-49 on pages 172173.