METR 104: Our Dynamic Weather (Lecture w/Lab) Thought Questions on the Seasons Dr. Dave Dempsey Dept. of Geosciences SFSU, Spring 2012

For the questions below, refer to the accompanying Figure 2-5.

1. In Figure 2-5, how does the sun angle (the angle between the sun's rays and a horizontal surface) at solar noon generally vary with increasing latitude? What does this imply about the intensity of sunlight at high vs. low latitudes?

2. Several globes are positioned around the room, simulating the position of the earth as it orbits the sun (represented by an overhead or slide projector at the center of the orbit). Notice that globes (should be) positioned so that the axis of rotation of each globe points in the same direction, just as it does (pointing toward Polaris, the North Star) when the real earth obits the sun.

1. What time of year is it at the position of each globe? How can you tell?

2. In Figure 2-5, which figure (a, b, or c) corresponds to each globe? What perspective (that is, from where in space) does the figure show your globe?

3. At each time of year shown, how does the length of daylight seem to vary with latitude? How can you tell?

4. Note the length of daylight at San Francisco's latitude at each time of year shown. Does it seem to vary with time of year? If so, describe the variation.

5. Note the sun angle at solar noon at San Francisco's latitude at each time of year shown. Does it seem to vary with time of year? If so, describe the variation.

3. The seasons are defined in terms of variations in length of daylight and sun angle at solar noon. Why do these two quantities vary over the course of the year? At what latitudes does this variation seem to be the greatest? What are the seasons like there, compared to here?

4. Bonus Questions: In Figure 2-5, in each of the figures (a), (b), and (c), when does the sun rise (before 6 am, at 6 am, or after 6 am)? When does it set (before 6 pm, at 6 pm, or after 6 pm)? How can you tell?

In each figure, in what direction (that is, where on the horizon) does the sun appear at sunrise and sunset? Does this vary with latitude in each figure? [Hint: east is always in a direction along a latitude circle; north is along a longitude circle toward the North Pole.]

(There are many more questions of this sort that these diagrams can help you answer—the topic is very rich.)

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