NAME: _________________________________________________ QUIZ SECTION: ____________
ATMS 101 Autumn 2008
Homework #5 (Due Wednesday, November 12)
Please show all work and write neatly in the space provided.
1. Examine the causes of the circulations involved in summer monsoons, winter monsoons, land breezes and sea breezes. Explain (in two sentences or so) how sea breezes are similar to summer monsoons. Your answer should reference differences between land and water that lead to temperature differences that are important to the formation of these phenomena.
Sea breezes and summer monsoons are both associated with warmer land and cooler water, resulting in convergence, rising air, and enhanced precipitation over land (summer monsoons are a seasonal circulation, while sea breezes are a diurnal circulation).
2. Explain how air circulations keep the Sahara desert dry in the winter.
There is large-scale sinking air over land in the winter months because of cooler surface temperatures over land. Sinking air leads to drying.
3. Explain why many years of temperature data must be used when determining the average temperature of a season.
Interannual variability is the reason. (It is caused by many things, such as El Nino, volcanic eruptions, frequency of sunspots, and other natural occurrences that have time-scales longer than a year.)
4.
Glance at several news articles that cite El Niño or La Niña as a reason for
“abnormal” weather that was observed at a particular location. Hint: a search from news.google.com will provide more than sufficient material. After you make a search, you can specify a date range to search for articles; choose “all dates” so that not just recent articles show up. (Please write concisely throughout this question.) a) First example: choose an article that associates abnormal weather (e.g. wetter than normal, more stormy than normal, or colder than normal) with either La Niña or El
Niño for one location (e.g. Southern California). i. What geographic region is affected in this article? ii. This article concerns (circle one):
El Niño La Niña iii. Describe the weather that this article associates with El Niño (or La
Niña). Include the year and (if included) season that the weather occurred.

iv. What is the internet web address of this article? b) Second example: choose an article that is associated with a different region. i. What geographic region is affected in this article? ii. This article concerns (circle one):
El Niño La Niña iii. Describe the weather that this article associates with El Niño (or La
Niña). Include the year and (if included) season that the weather occurred. iv. What is the internet web address of this article?
(we graded based simply on completion and coherence) c) Different regions are affected by El Niño in different ways. Use your lecture notes and online lecture slides to explain why Washington State tends to experience dryer and warmer conditions during El Niño than during La Niña.
Online lecture slides provide graphics showing the effects of El Nino and La Nina on
Washington State. During El Nino, upper-level ridges are more common near
Washington State, which are associated with dryer, warmer weather. During La
Nina, the jet stream aims more directly at Washington State and heights are lower on average. We also accepted a few other somewhat-related answers (like jetstream splitting for El Nino). Quite a few students referenced effects of El Nino at the equator instead of in Washington.
5. What is the ozone hole? Why does the ozone hole occur over Antarctica in the winter and disappear in spring?
The ozone hole is a region over Antarctica that sometimes has severely depleted levels of ozone compared to the levels observed in different regions and at different times. This question should have been worded differently: we should have written
“END of winter” and “the END of spring”. We just graded that students answered what an ozone hole was and that they made a reasonable attempt at answering the second part of the question.
The ozone hole occurs over Antarctica at the end of winter when the sun first rises. Polar Stratospheric Clouds (PSCs) form over the continent in extremely cold temperatures. It is in these clouds that CFCs are able to react with O3 and break it apart.
6. Why does the Earth stay at nearly the same temperature?
Radiative equilibrium. (The amount of incoming radiation from the sun is equal to the amount of outgoing infrared radiation from earth.) Some students referenced the Greenhouse Effect, which is not relevant to this question.