IN-CLASS ACTIVITY 2
Factors Affecting Climate + Biomes
Group NAME________________________
1 _______________________________
2_____________________ 3_______________________ 4______________________
1. SOLAR RADIATION
What are 2 reasons temperature decreases with increasing latitude?
At N latitudes, the sun hits at an oblique angle causing energy to be spread over a
greater area (less/area). Also the sun travels through more atmosphere that absorbs
and reflects the sun’s energy and reradiates it back to space as heat.
Why does the N hemisphere have a > range in temperature than the S hemisphere?
(think of the ‘lake effect’ in Chicago…)
The N has a higher % land than the S. Land hasThe N has a higher % land than the
S. Land has a lower specific heat than water and hence changes temperature more
readily.
What causes seasonal changes in temperature at northern (and southern) latitudes?
As the earth rotates around the sun, the tilt of the earth’s axis causes N and S
hemispheres to alternate through the year in the amount of direct sun they receive.
2. WIND + OCEAN CURRENTS
What causes wind? The uneven temperatures on the earth causes different pressure
areas and wind is air moving from high to low pressure areas.
How does wind affect ocean currents? Wind drives ocean currents and gives them
their directionality.
How do ocean currents affect temperature of air? The dynamic exchange between
air and ocean causes temperatures of the air to reflect the temperature of the ocean.
Why do northern latitudes in Europe have deciduous and not boreal forests?
The ocean current (Gulf stream) comes from warm tropical areas and brings
greater warmth to air over Europe than occurs in Canada.
How do ocean currents affect precipitation on land? Air flowing over oceans picks up
moisture.. As this air moves over the cooler land, rainfall occurs.
Why do N-S wind (and ocean) directions get deflected to more W-E directions?
The coreolis effect results from the earth being round and rotating to the E at
different speeds at different places on the earth. Wind is deflected to the R in the N
and to the L in the S hemisphere.
How are patterns of wind direction the same? different? in N vs. S hemispheres?
The wind directions are mirror images in the N vs. S. They travel from W to E in
temperate zones and E to W in tropical zones.
What direction does the wind come from in Illinois? The wind comes from the West in
Illinois and the East (SE and NE) in the tropics?
In what direction do ocean currents flow in N and S hemispheres?
The currents move clockwise in the N and counterclockwise in the S hemisphere.
Are the waters hitting northern Chile hot or cold? They are cold because the current
is coming from the Antarctic. What type of vegetation do you expect to be there?
Desert grows in coastal Peru.
3. PRECIPITATION: HADLEY CELLS, INTERTROPICAL CONVERGENCE ZONE
What happens to temperature and water vapor content of air as it blows over oceans
from N and S to the equator? Both temperature and water vapor increase.
What happens when winds converge (collide) at the equator (ITCZ)? The air is forced
upward. (It rises).
What happens to air temperature as it rises? Air gets colder at higher altitudes.
Which can hold more water vapor? hot air or cold air? Hot air holds more water
vapor than cold air.
What happens to the water vapor as it rises at the equator? The cooling water vapor
condenses, resulting in heavy rain.
Where do the highest amounts of rain occur on the earth? What biome is there?
The highest rainfall occurs around the equator. The tropical rain forest occurs there.
4. Dry air in the stratosphere eventually sinks down to earth at what latitude? Dry
(cold +dense) air sinks at 30 degrees N and S.
What happens to temperature as this air descends? Air temperature increases.
…to water-holding capacity of this air? Water-holding capacity increases.
Where do the lowest amounts of rain occur on the earth? The lowest amount of rain
occurs at 30 degrees N and S. What biome is there? The deserts occur there.
Why does the Gobi desert exist at much higher latitudes in central Asia?
The Himalayan Mountains block the movement of moist air resulting in a desert.
Do Hadley cells and the ‘solar equator’ stay stationary throughout the year?
Why?
The ‘solar equator’(and ITCZ) moves N and S of the equator because
the location of the sun’s direct radiation moves seasonally.
What is the highest latitude of the ITCZ during the year? The highest latitude of the
ITCZ is 23 degrees N and S. Why? The earth’s tilt on its axis is 23 degrees, thus
affecting the most N and S latitudes where the sun hits directly.
What affect does this movement have on seasonal rainfall in tropical latitudes?
This movement causes seasonal rainfall; when the ITCZ is overhead, it rains more
and when it is farthest away, it doesn’t rain.
What type of biome do you expect at 20 degrees north (e.g. Mexico)? Areas 20
degrees north will have tropical seasonal (deciduous) forest that drop their leaves in
the dry season.
LOCAL EFFECTS ON CLIMATE
1. Is the climate of northern California or central Illinois more arid?
more variable?
Illinois has a more arid and variable climate than N. California, Why? It is farther
away from the ocean, the largest source of evaporation, and it has a low specific heat
causing its temperatures to swing over a greater range.
Which area has trees with frost resistance? Year-round growth? Illinois has trees with
frost resistance, while California trees grow year-round.
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What happens to temperature as air goes up a mountain? The air cools. Why? The air
is under less pressure and expands in volume; the molecules are farther apart, have
less energy, and the temperature cools.
How do biomes change up the Rocky Mts.? Start at the bottom with deciduous forest.
The deciduous forest changes to boreal forest which changes to tundra at the top.
How do altitudinal and latitudinal transects of N hemisphere biomes compare? The
biomes change in the same order as one travels up a mountain or up the earth toward
the poles. Why? Climate changes are comparable in the two transects.
2. The Sierra Nevada and Cascade Mountains run N-S in the interior of our most
Western states. From what direction does the wind come from in those states? At
temperate latitudes the wind comes from the West.
Is the air moist or dry as it moves onto land? The air coming off the Pacific Ocean is
moist.
Recall what happens at the equator as winds from N + S meet resistance. Use that
knowledge to summarize what happens to T and precipitation on the windward (Wfacing) and leeward (E-facing) sides of those mountains. The moist air is forced up
the mountain. The air cools causing the water vapor to condense, resulting in rain on
the windward side. As the air flows over the top of the mountain and descends on the
leeward side, the dry air warms, causing it to hold any moisture, resulting in low
rainfall.
What is meant by a ‘rainshadow’? A rainshadow is the dry area to one side of a
mountain. On what side of the mountains does it occur? It occurs on the leeward
side. What type of vegetation grows on each side of those mountains? Temperate
rain forest grows on the windward side; desert grows on the leeward side.
3. Would temperature be higher on a S-facing or N-facing mountain slope? S-facing
slopes getting direct sun have higher temperatures than N-facing slopes.
Would soil evaporation be higher on a S-facing or N-facing mountain slope?
Evaporation is greater on the warmer S-facing side than the cooler N-facing side.
Which slope has the more luxuriant vegetation? The cooler, wetter N-facing side has
more luxuriant vegetation than the warmer, drier S-facing side.
4. What has caused continents to change biomes throughout geological time
Continental drift
Mountain building and rain shadows
Changes in orbit, tilt, wobble of earth
Climate variation (past and present)
Human alteration in land cover
Why are the coal deposits of S. Illinois comprised of tropical vegetation? N.
America used to be located at more tropical latitudes with tropical vegetation before
continental drift moved it to its present N latitude.