biogeography climate biomes and terrestrial biodiversity
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Biogeography: Climate, Biomes, and Terrestrial Biodiversity. Benefits of Blowing Wind. Wind connects all life on Earth With no wind, the equator would be unbearably hot and the rest of the planet would freeze

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benefits of blowing wind
Benefits of Blowing Wind
  • Wind connects all life on Earth
  • With no wind, the equator would be unbearably hot and the rest of the planet would freeze
  • Transports nutrients such as dust rich in phosphates blowing across the Atlantic from the Sahara to help replenish the rainforests in Brazil and build up agricultural soils in the Bahamas
  • Iron rich dust blowing from China’s Gobi Desert falls into the Pacific between Hawaii and Alaska and stimulates growth of phytoplankton
  • Determines the type of animal and plant life found in major biomes and also influences global air circulation patterns
harmful effects of wind
Harmful Effects of Wind
  • Wind also transports harmful substances such as particles with banned pesticides blowing from Africa’s deserts to Florida and degrading or killing coral reefs
  • Asian industrial pollution degrades air quality along the Washington and Oregon coasts
  • Carries volcanic ash with trace minerals that circle the globe and cools the planet such as the eruption of Mt. Pinatubo in the Philippines
  • Soil is moved from place to place when left unprotected thus hastening soil erosion
what is weather
What is Weather?
  • Set of physical properties in the troposphere
    • Temperature
    • Pressure
    • Humidity
    • Precipitation
    • Sunshine
    • Cloud cover
    • Wind direction and speed
  • Computer models use data from balloons, aircraft, radar, etc. to forecast the weather in each box of a 7-layer grid for the next 12 hours
    • Other models project weather for next several days
    • Calculates the probabilities that air masses and wind will move
weather changeability
Weather Changeability
  • Weather changes as one air mass replaces or meets another
    • Cold air tends to sink and warm air rises
    • Dramatic weather changes occur along fronts
  • Fronts – boundary between 2 warm air masses
  • Warm front – boundary between a warm air mass and cooler one it’s replacing
    • Rises over cool air
    • Moisture condenses into droplets to form clouds such as high wispy clouds announcing first signs
    • Moist warm fronts can bring days of cloudy skies and drizzle

Cold front – leading edge of an advancing mass of cold air

    • Advancing cold air is dense and stays close to ground
    • Thunderheads are produced
    • As overlying warm air is pushed upward it cools and water vapor condenses to form droplets
  • High – cold air and clear conditions
  • Low – warm air and bad weather

Weather extremes

    • Tornadoes – areas of extreme low pressure and very high winds over land, water spouts over water
    • Tropical cyclones
      • Hurricanes in the Atlantic Ocean
      • Typhoons in the Pacific Ocean
      • They can kill and damage property
      • They can have long-term ecological and economic benefits
        • Flushes excess nutrients from land runoff
        • Channels can be cut to let seawater flood bays
        • Reduces brown tide
        • Increases growth of grasses
        • Increases production of commercially vital species
what is climate
What is Climate?
  • A region’s general pattern of atmospheric and weather over 30-1,000,000 years determined by
    • Average precipitation and temperature
    • Influenced by latitude, altitude, ocean currents
    • Affects where people live, how they live, and what they grow
  • Temperature and precipitation is caused primarily by the way air and water circulate on a round planet.
global air circulation and regional climates
Global Air Circulation and Regional Climates
  • Uneven heating of the Earth’s surface
    • Tropical regions near the equator are hot
    • Polar regions are cold
    • Temperate regions have intermediate temperatures
  • Seasonal changes in temperature and precipitation
    • Earth’s tilted axis is 23 ½o
    • Regions are tipped toward or away
  • Rotation of the Earth on its axis
    • Prevents air currents from moving due north and south
    • Force created by rotation – Coriolis Force which creates 6 huge convection cells (Hadley Cells) of swirling air masses
      • 3 north and 3 south of the equator
      • They transfer heat and water from one area to another

Long-term variations in the amount of solar energy striking the Earth

    • Caused by occasional changes in solar output
    • Caused by slight planetary shifts in which the Earth’s axis wobbles (22,000 year cycle) and tilts(44,000 year cycle) as it revolves around the sun
ocean currents affecting climates
Ocean Currents Affecting Climates
  • Water density and previous factors create warm and cold ocean currents
    • Currents driven by winds and Earth’s rotation redistribute heat and thus influence climate and coastal vegetation
    • Gulf Stream warms NW Europe
    • Equatorial currents warm Alaska and northern Japan
    • Currents mix ocean waters and distribute nutrients and dissolved oxygen
  • Upwellingsreplace surface water pushed away from land and by constant trade winds blowing along some steep western coasts
    • Cold, nutrient-rich bottom water
    • Bring plant nutrients from deep to surface
    • Support large populations of plankton, zooplankton, fish and fish-eating seabirds
el nino southern oscillation
El Nino – Southern Oscillation
  • Prevailing westerly winds weaken or cease and the surface water along South and North American coasts becomes warmer
  • Upwellings are blocked and primary productivity is reduced and a sharp decline in fish populations drops
  • ENSO can trigger extreme weather conditions over 2/3 of the globe, especially the Pacific and Indian Oceans
el nino cont d
El Nino – cont’d
  • In 1997 and 1998, the world experienced the strongest ENSO
  • Some models project that if Earth’s atmosphere continues to warm, El Nino-like weather will be the norm and cause major ecological and socio-economic problems
  • The 97-98 ENSO caused a mild winter in the North and Mid-West and blocked hurricanes along the Atlantic preventing loss of life and property damage
la nina
La Nina
  • El Nino is followed by a cooling counterpart called La Nina
    • More Atlantic Ocean hurricanes
    • Colder winters in Canada and the Northeast
    • Warmer and drier winters for the SE and SW and US
    • Wetter winters in the Pacific NW
    • Torrential rains in SE Asia
    • Lower wheat yields in Argentina
    • More wildfires in Florida
    • La Nina is worse than El Nino for the US
    • Evidence shows that US is moving into this pattern for the next 2-3 decades
how chemical makeup of the atmosphere leads to the greenhouse
How chemical makeup of the atmosphere leads to the Greenhouse
  • Greenhouse gases allow light, infrared radiation, and some UV radiation from the sun through
    • H2O vapor
    • CO2
    • O3
    • CH4
    • N2O
    • CFCs
  • Earth absorbs and degrades it to long wavelength infrared radiation (heat) which warms the air (greenhouse effect)
  • The amounts of these gases undergo minor fluctuations over hundreds to thousands of years
  • However mathematical models of Earth’s climate indicate that natural or human induced global warming taking place could be disastrous for all life on this planet