Transcript environmental science - Clinton Community College

Chapter 5
Climate & Biodiversity
Weather
• Short term physical properties of the
troposphere at a particular time and place
–
–
–
–
–
–
Temperature
Pressure
Humidity
Precipitation
Cloud cover
Wind speed and directions
Data Collection of Weather
• Meteorologists are the scientists that evaluate data
and predict weather based on cumulative
information that defines the current physical
conditions in the troposphere relative to a certain
place on Earth. Weather prediction is based on
information from the following sources:
–
–
–
–
–
Weather balloon
Aircraft equipped with sensors
Satellites
Computer modeling
Weather maps
Climate
• Climate is defined as the general
atmospheric or weather conditions typical
of an area over long periods of time. Some
indicators are:
– Average temperature
– Average rainfall or snowfall
Global Air Circulation
Five major factors determine patterns:
1. Uneven heating of the Earth’s surface
(more heat at the tropics)
2. Seasonal changes in temperature and
precipitation (tilting of the Earth)
3. Rotation of the Earth (convection cells)
4. Long-term variations in solar energy
5. Basic properties of water and air
Upwelling
• Oceans currents are driven by wind and heat from
the sun.
• Winds blowing onto the western coasts push
surface water away from land and is replaced with
cold, nutrient rich bottom water.
• El-Nino-Southern Oscillation (ENSO) occurs
when the westerly wind weaken, coastal waters
remain warm and normal upwelling is suppressed.
The ENSO affect can be devastating for many
species.
Greenhouse Effect
• Greenhouse gases – allow IR/VIS/UV light in
–
–
–
–
–
Water vapor (H2O)
Carbon dioxide (CO2)
Methane (CH4)
Nitrous oxide (N2O)
Synthetic chlorofluorocarbons (CFC’s)
• Greenhouse Effect – natural warming effect of the
troposphere (heat escapes and heat is absorbed)
Global Warming
• Global warming is explained as human
factors that may cause the greenhouse effect
to change in the direction of increased heat
retention in the atmosphere.
– Burning of fossil fuels
– Release of carbon dioxide, methane and nitrous
oxide into the atmosphere
– Precipitation patterns may shift
– Many habitats could be affected
Ozone Layer
• A band of ozone (O3) exists in the
stratosphere.
– UV radiation causes O2  O3
– Filters about 95% of the harmful radiation from
the sun
– Forms a thermal cap which helps maintain the
average temperature of the troposphere
– Loss or destruction of the ozone layer would
support global warming
Microclimates
• Small or local climate conditions
– Mountains disrupt the flow of surface winds
and storms (rain shadow effect)
• Surface air is cooled as it is forced to rise & expand)
• Windward (wind-facing) slopes experience most of
the moisture
• Leeward (away from the wind) slopes experience
drier air masses and draws moisture from plants
– Cities create microclimates due to the large
amount of buildings, concrete and traffic
The Earths Major Biomes
• Result primarily from differences in climate
• Biomes are not uniform but they offer different
communities
• Latitude (distances from the equator) have biomes
that become colder toward the poles
• Longitudes (distances from the prime meridian) go
from pole to pole – no effect
• Altitude (elevation above sea level) becomes
colder with increased elevation
Deserts
•
•
•
•
Evaporation exceeds precipitation
Sparse and widely dispersed vegetation
Low rainfall
Three classifications
– Tropical – hot & dry like the (Sahara)
– Temperate – high summer temps, low winter temps
with species that have adapted to limited water like
(Mojave)
– Cold – winter are cold, summers warm like (Gobi)
Grasslands
• Grasslands have enough annual precipitation to
support grass & a few trees
• Persist because of a combination of
– Seasonal drought
– Grazing by large herbivores
– Occasional fires
• Three types
– Tropical (savanna) - warm temperatures, 2 prolonged
dry spells & abundant rain
– Temperate - cold winters, hot/dry summers, sparse
precipitation
– Polar (tundra) - south of artic polar ice cap, bitter cold
Forest
• Undisturbed areas of vegetation, moderate to high
average precipitation
• Three types of forests
– Tropical
• Tropical rain forest
• Tropical deciduous forest (monsoon or seasonal)
• Tropical scrub forest
– Temperate deciduous forest
– Polar (boreal) or Evergreen conifer forests
Mountains
• Dramatic changes in altitude, climate, soil
& vegetation
• 20% of the Earth’s land surface
• Contain the majority of the world’s forest
• Help regulate climate
• Play a critical role in the hydrologic cycle
Saltwater Life Zone
• Types
–
–
–
–
–
Estuaries
Coastlines
Coral reefs
Coastal marshes
Swamps oceans
Estuaries
http://www.waikato.govt.nz/enviroinfo/coasts/coastalecosystems/estuaries/images/threats1.jpg
Coral Reefs
http://polarbearsmustnotdie.blogspot.com/2006/07/coral-reefs-are-dying-as-world-heats.html
Freshwater Life Zones
• Types
–
–
–
–
–
–
–
Lakes
Ponds
Streams
Rivers
Inland wetlands
Levees
Dredging canals
Inland Wetlands
Purpose of a Levee
How Levees Fail