Archive for July, 2006

Reading topographic maps can be confusing to some. Here are a few resources that may be of help:

Topographic Mapping from the USGS
Topographic map symbols from the USGS
Understanding topographic maps from Idaho State University
Interpreting a topographic map from Idaho State University
Landforms on topographic maps from Prof. Susan Clark Slaymaker (These are particularly helpful to study for lab quizzes using topographic maps.)

TPE Link: Maps

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A student recently asked “I was reading the last lecture in unit II and it mentioned sometime about ITCZ…. I remember reading about it in unit I but never really understood what it meant….???”

Well, the ITCZ stands for the Intertropical Convergence Zone, a broad belt of low pressure that straddles the equator. It is formed by the convergence of the trade winds. The convergence provides uplift for warm, moist tropical air producing copious rainfall in the equatorial regions of Earth

For more see:

The Intertropical Convergence Zone (Earth Observatory)
Understanding the ITCZ (Columbia University)

Geography 101 (On-campus) lecture notes
TPE Link: Global scale circulation

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A severe storm passed through Stevens Point, WI on July 24, 2006. Preceeding its arrival the sky roiled with mammatus clouds, a sure sign of instability and severe weather.

For more see:

Mammatus cloud (Wikipedia entry)

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In the first lab manual exercise you are required to calculate the noon sun angle. To do so you need to know the zenith angle. The zenith angle (Z) is “the number of degrees between a site location and the declination of the Sun.”

To calculate the zenith angle:

– Subtract site location and declination when they are in the same hemisphere. Example: Site location is 60N on June 21st the declination is 23.5N. Z=60 – 23.5 = 36.5


– Add the site location and declination when they are in different hemispheres. Example: Site location is 60N on Dec 22 the declination is 23.5S. Z=60 + 23.5 = 83.5

Then the noon sun angle is:

NSA = 90 – Z

Note in these examples that the declination is subtracted from or added to the site location. There may be a time when the site location has a smaller value than the declination yielding a negative Z.

For example:

A site at 3.5 S on Dec 22 (declination 23.5S).

Z = 3.5 S – 23.5 S = -20

Given that we can’t have a negative Z, just make it a positive number. It still is by definition “the number of degrees between a site location and the declination of the Sun.”

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The Coriolis Effect (or force) is a subject that is often confusing to
students. The Coriolis Effect is the effect of earth rotation on the
direction (and path) of the wind. Use the following sites to help you understand how the Coriolis effect works:

Observe an animation of the Coriolis effect over Earth’s surface.
(Exploring Earth)
Observe how the Coriolis effect influences wind direction. (Exploring Earth)
“Getting Around The Coriolis Force” (David J. Van Domelen)
Shoot a cannon at a ship to see the Coriolis effect at work.

There are a number of incorrect perceptions of the Coriolis effect, like the reversal of water movement stepping over the equator. This “bad meteorology” is addressed here.

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The Review tools for tests guide at the Study Guides and Strategies site provides helpful hints to prepare for tests.

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The Study Guides and Strategies site covers every aspect of learning whether in a traditional classroom or online, on your own or as a group. Highly recommended.

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