These are the answers to the questions at the end of the Chapter. Try to answer them
first, before relying on the answers provided below!
1. The difference between weather and climate is one of time. Weather occurs over
short time periods. Climate is measured over years or decades.
2. I’d say Madison was Dfb – no dry season, and a warm summer. This is much like
central Europe. Note that the Dfa climate over the southern US doesn’t have a
3. Climates at the Poles have different surface conditions (snow and ice) than the
bare surface in the tropics. In addition, the solar forcing at the tropics is pretty
constant during the year, but it varies wildly at the Poles.
4. To farmers: First and last freeze and frost dates. Rainfall totals and distribution
of rain throughout the year. City planners will need to know about extremes of
weather that will cause infrastructure stresses. What are the extremes of rainfall,
and how can they be handled by sewers? Will the population be threatened by
temperatures that occur throughout the year? What kinds of storms are possible?
5. Well, the classification scheme would have to consider when temperatures are
below freezing and when precipitation occurs. If the precipitation falls when the
temperature is warmer than freezing, then that’s the place for the snow phobes.
6. You could use wind speeds, or wind directions, to help classify the climate.
Number of days with cP, or mP, or mT, or cT airmasses.
7. Pollen from crop plants that get trapped in lake sediments would be helpful.
Smoke/ash from fires can get locked into glaciers.
8. The deepest layers of ice on a glacier are oldest because snow falls on top of the
glacier and doesn’t melt, and the glacier slowly gets thicker and thicker as snow
continues to fall on the top of the glacier.
9. The Little Ice age (p. 433 in the text) was a period from 1400 to 1850 when
Europe was significantly colder than it is now. An example given in the book:
The Thames in London froze over 11 times in the 1600s, and it hasn’t frozen over
in the past 100 years. It wasn’t a true ice age, as there were not widespread
glaciers (although mountain glaciers did increase in size)
10. Lower sea levels occur during ice ages because the glaciers hold a lot of water.
When the glaciers melt, the water returns to the oceans and ocean levels rise.
11. The tree rings on the trees can be compared to tree rings today – how does the
growth rates compare. You can use the growth rate as a proxy for temperature.
You needn’t know exactly when the trees were felled – but a variety of trees
should give similar signals, and those different signals can be used to benchmark
12. Plate Tectonics: Large regions of earth are floating on top of the magma center
and those regions are moving. Where plates collide, mountains can grow. As
land becomes higher, its climate can change radically. Further, as continents
move away/towards the Equator, the climates on the continents can change.
Climate can also change as Ocean Basins open up or close. For example, if North
and South America separated, and the Atlantic/Pacific Oceans could mix, climate
13. Mass extinctions could be caused by sudden melting of the Greenland or
Antarctic ice sheets. The fresh water, especially if it floods the north Atlantic,
will shut off the thermohaline circulation, altering the climate around the north
Atlantic. Mass extinctions could also arise from large volcanic eruptions, the
ejecta of which could cause significant cooling. Or asteroid impacts.
14. A mile-high ice sheet will have a big affect on albedo. Its weight will cause the
Earth to be pushed down. Flow off the ice sheet will warm adiabatically, but its
coldness will prevent poleward flow of warm air. Poleward air would have to rise
dramatically at the ice sheet, so that’s a good source of vertical motion. The
boundary of the sheet would be a semi-permanent frontal zone, too, so you would
expect to see a jet stream above the edge of the sheet.
15. Asteroids that cause craters can be incinerated by the atmosphere. Asteroids that
hit the ocean will not cause craters. Geologic forcing and erosion can obliterate
the presence of the crater.
16. The Maunder Minimum occurred about the time of the Little Ice Age and it
relates to the few sunspots observed during that time. Fewer sunspots meant a
cooler sun (less radiation), and probably less solar forcing on Earth. The Younger
Dryas is a period of enhanced cooling about 11000 years ago. It is hypothesized
that the cooling occurred because lots of fresh water flooded the north Atlantic as
the Laurentide Ice sheet melted. That fresh water altered the oceanic circulation
in such a way to cool Europe.
17. Orbital changes in the next 50000 years don’t look like they’ll have a big effect –
precession changes are very small, Eccentricity is dimishing, which means
seasonal differences in radiation will be small, which does not encourage glacial
growth. Glaciers are preferred when the summers are coolest: Earth is far from
the Sun in summer, the tilt is small, and eccentricity is large.
18. NH is warmer in summer and colder in winter because there’s more land.