Factors Affecting Wind

Climate- A Wind of Change

Friction• Friction acts to slow air movement, which

changes wind direction.

• Jet streams are fast-moving rivers of air that travel between 120 and 240 kilometers per hour in a west-to-east direction.

• Mountain-building can cause the jet to be force to move around it, causing climate changes locally.

Climate generalizationsFind: Heat low, Bermuda High

ITCZ

Local Winds

Special Climate/Wind topics

The local winds are caused either by topographic effects or by variations in surface composition—land and water—in the immediate area.

• In coastal areas during the warm summer months, the land surface is heated more intensely during the daylight hours than an adjacent body of water is heated. As a result, the air above the land surface heats, expands, and rises, creating an area of lower pressure. At night the reverse takes place.

Land and Sea Breezes

Sea and Land Breezes

Local Winds

19.3 Regional Wind Systems

• In mountainous regions during daylight hours, the air along the slopes of the mountains is heated more intensely than the air at the same elevation over the valley floor. Because this warmer air on the mountain slopes is less dense, it glides up along the slope and generates a valley breeze. After sunset the pattern may reverse.

Valley and Mountain Breezes

Valley and Mountain Breezes:which one is the mountain

breeze?

Reminder:

Wind Systems

• The prevailing wind is the wind that blows more often from one direction than from any other.

Wind Direction

• In the United States, the westerlies consistently move weather from west to east across the continent.

• Monsoons are the seasonal reversal of wind direction associated with large continents, especially Asia. In winter, the wind blows from land to sea. In summer, the wind blows from sea to land.

El Niño and La Niña

Ocean variables that effect climate:

• At irregular intervals of three to seven years*, these warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters. (>intensity, >time)

El Niño• El Niño is the name given to the periodic

warming of the ocean that occurs in the central and eastern Pacific.

• A major El Niño episode can cause extreme weather in many parts of the world.

Normal Conditions

Definition: Warm Waters in the eastern S. Pacific (Peru/Chile)

El Niño Conditions

El Niño and La Niña

Regional Wind Systems

• Researchers have come to recognize that when surface temperatures in the eastern Pacific are colder than average, a La Niña event is triggered that has a distinctive set of weather patterns.

La Niña

Sea-Surface Temperatures: Using the color key below, is this situation an El Nino or a La Nina?

North Atlantic Oscillation index

• Negative NAO= colder winters in

N. America and Europe ..2008-9(due to a weak Icelandic low subtropical high)

• Positive NAO= Mild and wet winters (due to stronger subtropical high pressure and a deep,

lower than normal Icelandic low)

Volcanoes and Climate

• Particulates (Dust and Ash)

• Aerosols (Fine particles that stay aloft)

• Sulfur Dioxide (add water)

• If material is ejected into the stratosphere, it can remain for years, cooling the planet

• 1991 (Mt. Pinatubo), Tambora (1815) –Caused the “summer that wasn’t” (USA/Europe

Mt. Redoubt, Alaska 100 miles sw of Anchorage.

Volcanoes in the Cretaceous

• Volcanoes also erupt Carbon Dioxide

• During this time, there was extensive volcanic activity, causing a great rise.

• Planet warmed extensively *

• 150 MYA

MtMt. Redoubt steam eruption 3/22/09Mt.

THE SOLAR RADIATION VARIES DUE TO CHANGES IN EARTH’S TILT, REVOLUTIONLESS INSOLATION IN HIGH LATITUDES IN SUMMERAN INCREASE IN SNOW, SO IT LASTS LONGER (ALBEDO)

Milankovitch Theory: Orbital Variations and Glaciation

(three)

66% more solar energy in Jan now.When more elliptical, 20-30% more energy at perihelion than aphelion. Presently, the orbital eccentricity is nearly at minimum.

41

ETiTilt varies from 21.5 to 24.5 degrees

Precession: The slow wobble on Earth’s axis• 23,000 years for a complete cycle

The Greenhouse Effect-CO22

125 Year average

Past CO2•

reference

How can we know temperatures 400,000 years ago?

• Ratios of 17O and 18O in ice reflect the climate at the time that snow fell

CO2 Methane Temperature

past 800,000 years

Recent CO2 on Mauna Loa

Temperatures over the last 1,000 years(multiple sites around the globe)

U.S.A. Leads the world in usage of fossil fuels- we should lead in solving the problem also!

Sea level rise ALREADY seen

Prediction models for the future

reference

Polar Sea Ice minimums

Changes in Sea Ice Thickness

How much ice is left?

Ice massVolume

(1000 km3)Potential sea level rise (m)

Mountain glaciers and

small ice caps180 0.5

Greenland 2620 6.6

West Antarctica

3262 8.1

East Antarctica

26,039 64.8

Consequences of Rising Oceans

•

Other countries at risk

Solar activity- Maunder minimum until the present

reference

Solar activity and Temperature 10,000 yrs

•

Tuvalu- A drowning country