Review the following barometric pressure maps for January and July (Figure 6.11 in your text) and answer the following questions.

This activity contains 6 questions.

	Seasonal shifts in wind and pressure systems are one of the primary driving forces behind the seasonal differences in precipitation in many parts of the world. In the maps above, compare the positions -- especially the latitudes -- of 1) the ITCZ and 2) the large sub-tropical high pressure cells. You should be noticing that they all shift roughly in the same direction at the same time of year. Briefly describe the direction and timing of this shift, and provide a brief explanation of why the shift occurs. (See hint.)   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Focus now on the ITCZ in both maps. What time of year is it positioned over Northern Australia, and what should this tell you about the timing of the rainy and dry seasons in that part of the world? In other words, what type of weather is generally associated with the ITCZ?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Now shift your attention to the Mediterranean climate locations, which are found along the western edges of continents between about 30-40 degrees latitude -- in BOTH hemispheres. Using this rule as your guide, find California's Mediterranean climate and then find the Pacific Sub-tropical High Pressure cell, which is usually somewhere over the Pacific, west of California. Describe how this pressure cell changes in strength (millibars) and latitude (degrees) during the course of the year. Make sure to provide actual numeric values in your description.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	This is a climagraph for San Francisco, California, located at 37.5 degrees North. Based on your observations from the previous question, how does the position and strength of the Pacific Sub-tropical High Pressure cell affect the seasonality of precipitation in San Francisco. Be explicit about this connection; make sure to mention both January and July conditions.   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	The position of the sub-tropical high pressure helps us understand the dry season for San Francisco, but what explains the wet season? In other words, what is the name of the important wind system that shifts into place over much of California during winter, and what type of storms does it bring?   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

	Valparaiso, Chile is located on the west coast of South America at about 33 degrees South latitude. It has a climate extremely similar to San Francisco's, with a critical differnce. What is this difference, and how does it relate to the sub-tropical high pressure cell which sits over the Pacific Ocean west of Chile? Look at the maps!   To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.

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