Natural Variations in Climate

1. El Nino and La Nina

• Natural changes in climate due to warmer or cooler than normal surface water in the eastern Pacific

Normal Conditions/Trade Winds

• Normally, strong trade winds blow from the east along the equator, pushing warm water into the Pacific Ocean.

El Nino• El Nino – unusual ________ of ocean

temperatures of Pacific Ocean

• results from weakened or a reverse in trade winds in the western Pacific Ocean, allowing piled-up warm water to flow toward South America.

warming

El Nino Weather in the US• Northeast United States is warmer

• Western US is stormy

• Southern US is cold and wet

La Nina• unusual _________ of ocean temperatures of

Pacific Ocean• Results in stronger low-level winds along the

equator• Northern US harsh winter conditions• Southern US drier and warmer condition

cooling

El Nino or La Nina – 2014/2015?

El Nino La Nina

Based on our winter, do you think its an El Nino year or a La Nina year?

2. Solar Cycle

3. Ice Ages

• Milankovitch Cycle – Gradual changes in Earth’s rotation and orbit have changed the intensity of sunlight received in our planet’s polar and equatorial regions

Ice Ages are cyclic.

The last one occurred ~12,000 years ago

The exact cause of what triggers an ice age

is not known

Earth’s Tilt

Earth’s Wobble

Currently points toward Polaris but every 13000 years it will point toward Vega

Earth’s orbit

• B.

http://www.youtube.com/watch?v=gaJJtS_WDmI

4. Volcanic Eruptions

Large quantities of Volcanic Ash that are released into atmosphere which blocks incoming solar radiation,

Thus, cools the earth

Mt. Pinatubo

• Erupted in 1991, caused cooler temps around the world for about 2 years.