p228, 1-20, omit 6, 7, 17
1. a) The tilt of Earth’s axis of rotation produces the seasons. The Sun’s rays shine directly on Earth’s
surface between latitude 23.5o N and 23.5o S. (..Between 0o and 23.5o N for six months of the year, between 0o
and 23.5o S for the other six months of the year. Over a year there is a net gain of heat at low latitudes and net
heat loss at high latitudes.
b) If Earth were not tilted, there would be no seasons (…in theory. If we could somehow “fix” the tilt, who
knows what all the interconnectedness between the oceans and atmosphere would produce.)
2. a) Along the Arctic Circle, on the summer solstice, the Sun is up most of the day circling low in the
sky, but at midnight dips to the horizon (before rising again.)
b) During the winter solstice it would be dark all day except near noon when twilight would brighten, and you
think you’re getting a sunrise, but no, twilight fades and darkness falls again
3. Temperatures at the poles (high latitudes) and tropics (low latitudes) does not vary
4. - The atmosphere is composed of three main gases, in order, nitrogen, oxygen, and argon.
- In the troposphere, temperature decreases with increasing altitude. At Earth’s surface, the atmosphere in
equatorial regions is warmer than at polar regions…
- Density of air is controlled by pressure, temperature, and moisture content/humidity.
- Moisture content/humidity is the amount of H2O vapor contained in air. Water vapor increases in air when
air is warmer and when there is a source of moisture. (Hmm, what’s a good moisture source on planet Earth…)
- Air pressure exerted on Earth’s surface is controlled primarily by temperature and moisture content of air.
- Cold, dry air is denser and sinks toward the ground; warm, moist air is less dense and rises away from the
ground. Air always moves from high pressure to low pressure. This simple fact is the source of most winds
on earth.
5. The Coriolis effect causes a deflection of motion in objects that move for a long time or a long distances
across lines of latitude. Because of the west-to-east rotation of Earth, the Coriolis effect causes deflection to the
right in the Northern Hemisphere and to the left in the Southern Hemisphere. The Coriolis effect is greater at
higher latitudes because the rate of change of the rotational velocity increases toward the poles. The difference
in rotational speeds at different latitudes gives the magnitude of the Coriolis effect. The difference in
rotational speed from 60o to 90o is four times greater than that between 0o and 30o. (Another way of
thinking of this is simply to imagine the smaller circles of latitude around the poles as a “tighter curve” than the
rotation path at low latitudes. What generates greater centrifugal “force,” a gradual curve on the interstate at 70
mph? Or a tight turn in your neighborhood at 10 mph?)
(Skip 6 & 7)
8. Weather describes local and short-term changes in atmospheric conditions (e.g., temperature, rainfall,
pressure, winds). Climate looks at averages of atmospheric conditions over a much longer term. Rainfall
during one day does not make an area have a wet climate. If it rained for many days during the summer, for
example, year after year, then we might say that area had a wet summer climate.
9. Coriolis effect deflects motion to the right in the Northern Hemisphere. In an area of low atmospheric
pressure, winds flow inward (from high pressure to low pressure). These inward-flowing winds are subjected
to the Coriolis effect which causes a veering of the inward flow to the right and produces counterclockwise or
cyclonic flow. Winds flow clockwise or anticyclonic around a center of high pressure.
THAT’S THE BOOK’S ANSWER, but to me it’s confusing. If a large rotating system (ocean current) is pulled
DOWN by gravity, the rotation is clockwise in the northern hemisphere (think of the Gulf Stream in the North
Atlantic). If a large rotating system goes against gravity and rises up (the definition of LOW PRESSURE aka a
STORM SYSTEM) it rotates in the opposite direction. I use the path of the Gulf Stream to remember not only
ocean current rotation but hurricane/tornado rotation as well.
10. Sea breezes and land breezes form due to differences in heat capacity between land and ocean.
- During the day, land areas are warmer (they have lower heat capacity) and warmed air above land rises.
Cooler air over the ocean replaces the rising warm air. A sea breeze flows from ocean (higher air pressure)
to land (lower air pressure).
- A land breeze is the opposite and occurs at night. During a hot summer day, we would expect a sea breeze
because land is warmer than ocean.
11. Polar air masses: continental polar, Arctic polar, and maritime polar;
- tropical air masses: maritime tropical and continental tropical. Polar air masses are moved primarily by
the westerlies from the North Pacific Ocean across the U.S. Northwest and from central Canada across the
Midwest and Northeast. Tropical air masses are moved primarily by the trade winds and by the jet stream
and affect primarily the southern half of the contiguous United States.
- Heavy rain/snow and thunderstorms (hail) are typically associated with cold fronts, and moderate to light
persistent rain/snow is associated with warm fronts.
12. Tropical cyclones require rising warm, moist air, warm ocean water (to provide warmth and moisture),
and sufficient Coriolis effect to cause rotation. Tropical cyclones form in tropical regions and are pushed
to the west by the trade winds. - Midlatitude areas seldom experience hurricanes because they are usually not
warm enough.
- The equator has too small a Coriolis effect to cause the necessary rotation.
13. High winds cause great damage (destroy buildings, etc.) and heavy rainfall causes flooding. Storm surge,
the rise in sea level associated with a hurricane’s low atmospheric pressure, causes the most damage to
property
14. Climate patterns are dictated primarily by distance from the equator (latitude) but these bands are
deformed slightly by the movement of the world’s winds and ocean currents. For instance, climate zones are
slanted away from the equator in areas where ocean currents flwo away from the equator (gulf stream, for
example) and oceans flow the way they do mostly because of wind movements.
15. The Titanic sank because it sideswiped an iceberg. The iceberg slashed a 100-m-long opening in the hull
below the waterline, and the Titanic filled with seawater. The International Ice Patrol was established two years
later to prevent similar tragedies.
16. - Sea ice is formed by freezing of seawater under conditions of extreme cold (polar winter).
- Icebergs break off from the ends of glaciers that form by accumulation and packing of snow.
(skip 17)
18. Discuss the greenhouse gases in terms of their relative concentrations and relative contributions to any
increased greenhouse effect. CO2 and H2O are the most potent greenhouse gases. There are others, (methane,
etc) but none affects the earth’s greenhouse effect the way CO2 does.
19. The iron hypothesis is the idea that, since oceans that have low iron also have low
activity/productivity, we should add iron to iron-poor areas to try to increase oceanic productivity. This
technique has shown to be effective, but implementing it is difficult, expensive, and the long-term effects of it
are just as likely to be detrimental as beneficial.
20. A SOFAR sound channel (Sound Fixing And Ranging) is a layer of ocean water that, because of varying
water density and temperatures, traps -- in the layer -- sound waves that occur above or below the layer. (this is
the same repeated reflection within a medium of differing density that fiber-optic cables are based upon)
Whales are thought to use this “acoustic pipeline” to communicate of very long distances under water.
Because sound travels faster in warmer water, scientists are seeing if sound waves can travel faster in the
SOFAR channel year after year, because of global warming.