factors affecting wind climate- a wind of change friction friction acts to slow air movement, which...
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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