Transcript 6-2 Climate and Biomes

6-2 Climate and Biomes
Fig. 5-9, p. 106
Where is the water and life at?
A closer look at the relationship
between latitude, solar energy, and
climate.
• Some facts to know:
• Earth receives energy from the sun – the
light rays strike the surface essentially
parallel to each other.
• The earth’s orbit is elliptical and it is closer
to the sun at some times of the year and
farther away at other times of the year.
• What day are we closest to the sun?
• January 3
• What day are we farthest away from the
sun?
• July 4
• What does that mean about the relationship
between distance from the sun, temperature,
and seasonal differences in temperature?
Some more facts..
• The earth’s surface is curved.
• The earth is at a tilt relative to the sun as the earth orbits the sun during the year
there are times when the northern
hemisphere is titled toward the sun and at
other times of the year the northern
hemisphere is tilted away from the sun.
Fig. 5-3, p. 102
Because the intensity with which light rays
strikes the earth’s surface varies……..
• Daylight length varies.
• The farther away from the equator (north or
south) …
– . Light is less intense as it strikes surface at less
than 90 degree angles.
– Longer daylight length in the summer.
– Seasons based on temperature.
How does light intensity
determines temperature?
• Near the equator light rays strike the earth at a 90
degree angle (perpendicular) during much of the year.
Temperature remains mostly constant throughout the
year. (varies from tropic of Cancer and Capricorn)
• Greatest degree of heating occurs at the equator.
• Away from the equator, because of the curve of the
earth and the tilt of the earth, the light rays strike the
earth at angles less than 90 degrees (relative to the
perpendicular).
• Less intense light = less heating.
What are the physical properties of air how do
they affect current, temperature, and climate?
• Hot air rises.
• Rising air creates areas of low pressure and that
draws more air behind it.
• Rising air cools and descends creating a cycle of
circulating air called “Hadley cells”.
• Hadley cells are located at roughly 30 degree
intervals of latitude.
– Midlatitude deserts are caused by the descent of
formerly tropical air that is dry and warms as it
descends.
Fig. 5-5, p. 103
Fig. 5-6, p. 103
Fig. 5-4, p. 102
Water Properties and Ocean
Currents
• Water has different densities at different
temperatures.
• Warm water is less dense than cold water – that is
until it freezes. (then it becomes less dense and
floats)
• In aquatic systems, warm water rises and cool
water sinks.
• Ocean currents are a combination of circulating
water due to temperature, wind currents that move
water, and rotation of the earth.
Fig. 5-2, p. 101
How Biomes are determined by
climate?
• The biome that exists in any given area will
be determined by both temperature and
rainfall.
• Look at page 124 in your text. Figure 6-21
• Vegetation types vary = Biomes vary.
Climate Regions
• Tropical – warm year round
– 23.5 N – 23.5 S
• Temperate – distinct warm and cold/cool
seasons.
– 23.6N to 66.4 N, 23.6 S to 66.4 S
• Polar – cool or cold year round
– 66.5 N to north pole, 66.5 S to south pole.
What other factors affect the type of
Biome that may exist in any given
area?
• Local climate (microclimate)
• Soil conditions
• Natural and human caused disturbances.
As a result of local variations, biomes do not exist as uniform
ecosystems within the boundaries shown on the map. In reality,
they are a patchwork of similar ecosystems that sometimes
overlap.
North- and south-facing slopes, showing microclimates, Southern California.
Ecotone
• Transitional zone between overlapping
ecosystems (and biomes).
• Shows characteristics of both systems.
• A “blended” ecosystem.
El Nino and La Nina – ocean temperature
extremes that affect weather world-wide and
occur every 2-7 years.
• El Nino – Southern Oscillation (ENSO)
– westerly winds over the Pacific ocean weaken, which allows the
ocean water along the western NA and SA coast to becomes
warmer.
– Changes the patterns of ocean upwelling off the coast which
affects ocean organisms and the fishing industry.
– Can trigger extreme weather changes in certain parts of the world
especially land along side Pacific and Indian Oceans
• Drought in Southern Africa, Southern India, Sri Lanka, Philippines,
Indonesia, Australia, Southern Peru, Western Bolivia, Mexico,
Central America
• Heavy rain and flooding in Bolivia, Ecuador, Northern Peru, Cuba,
U.S. Gulf States
• Hurricanes in Tahiti, Hawaii
La Nina
• Larger than normal amount of cool ocean surface
water in the pacific, sometimes (but not always)
follows an El Nino year. Typically they last 9-12
months up to 2 years.
• Effects are usually opposite of El Nino.
• Based on the following map, are we in an El Nino,
La Nina or neutral year?