In the movie “The Day After Tomorrow (2004)”, the climatologist character (played by
Dennis Quaid) claims that air from the tropopause region and lower stratosphere will be
freezing cold when brought to the surface. Explain why he was wrong (no need to watch the
movie to explain that ;).
[Hint: To answer this question, combine knowledge learned from chapters 1 and 6 on the
temperature structure of the atmosphere and on lapse rates.]
2. The following questions concern the weather chart shown in Fig. 1. Assume that at the
shown altitude level the winds at points A and B are described by air flow in geostrophic
balance (here ignoring slight curvature effects).
a) Draw and label arrows in Fig. 1 at points A and B indicating:
(i) the direction of the pressure gradient force (PGF);
(ii) the direction of the Coriolis force and its strength relative to the PGF;
(iii) the wind direction.
b) Qualitatively, where will the geostrophic wind be stronger, at point A or B? Explain
briefly the physical reason leading to your conclusion.
• Provide hand-written or typed answers to the following questions (max. 10 points per
numbered block of questions).
• Submit a hard copy of your answers at the beginning of class on the due date or before
(staple your answer sheets to the question sheets).
• Make sure that your first and last name are stated at the top right corner of the answer
sheets.
• Each sub-question should be answered concisely in 2 – 4 sentences (state the key points
and briefly explain your reasoning).
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Fig. 1: Simplified weather chart with constant pressure contours (isobars, units of hPa) at an
altitude of 3000 m for a region in the Northern Hemisphere.
3. Look again at Fig. 1, but now consider the direction of the winds close to the low pressure
center (L). For this question, assume that Fig. 1 would represent a situation at the surface.
[As a side note: on such a surface chart, the isobars showing sea-level pressures would have
values about 300 hPa higher than indicated in Fig. 1; however, this is irrelevant for
answering the following question].
Explain qualitatively how and why the winds (direction and relative strength) close to the
low pressure center at the surface would deviate from the gradient wind direction at 3000 m
altitude (consider the forces involved, assuming the curving of the isobars would look exactly
the same near the surface).
4. Sea breezes and land breezes / mountain and valley breezes.
a) Why is it typical for clouds to form over land with a sea breeze, while over the sea clouds
tend to form with a land breeze?
b) How would the strength of a valley breeze (a mountain anabatic wind) on a sunny
afternoon be influenced by the presence of snow covering the mountain top and its upper
slopes?