CLIMATE CYCLES Chapter 14 Lesson 2 Longterm cycles

CLIMATE CYCLES Chapter 14 Lesson 2

Long-term cycles ■ Earth has experienced many major atmosphere and climate changes in its history. ■ Ice Ages are cold periods lasting from hundreds to millions of years when glaciers cover much of Earth. ■ Glaciers and ice sheets advance during cold periods and retreat during interglacials- the warm periods that occur during ice ages or between ice ages.

Causes of long term climate change ■ One factor that affects how much energy Earth receives is the shape of its orbit. ■ Another factor that scientists suspect influences climate change on Earth is changes in the tilt of the Earth’s axis.

Short Term Cycles ■ Seasons ■ Solstices- Summer Solstice June 21 or 22, Winter Solstice December 21 or 22. ■ Equinoxes- Number of daylight and nighttime hours are almost the same. Spring Equinox is March 21 or 22, Fall Equinox September 22 or 23. ■ (Dates are references to the Northern Hemisphere- it would be the opposite season in the southern hemisphere. )

El Nino and the Southern Oscillation ■ The combined ocean and atmospheric cycle that results in weakened trade winds across the Pacific Ocean is called El Nino/ Southern Oscillation. ■ A complete cycle happens every 3 -8 years. It affects the strength of storms.

Monsoons ■ Another climate cycle involving both the atmosphere and the ocean is a monsoon. ■ A monsoon is a wind circulation pattern that changes direction with the seasons. ■ The world’s largest monsoon is found in Asia. Cherrapunji, India is one of the world’s wettest locations.

Droughts ■ A drought is a period with below-average precipitation. ■ A drought can cause crop damage and water shortages. It usually coincides with a heat wave.