Lab 2b: Understanding insolation and surface temperature
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Understanding insolation and surface temperature
In this section you will examine the relationship between insolation, seasons and surface
temperature. We will look at three maps: January and July insolation, January and July surface
temperature, and the seasonal change in surface temperature. I am first going to walk you
through each visualization, then we will explore their relationships. The worksheets are based on
the visualizations below. While you do not have to turn in the worksheets, I encourage you to
color them as that often helps you to understand what they are showing.
Worksheets
Worksheet 1 shows the incoming solar energy in January and July. Color in the legend and the
visualizations.
Worksheet 2 shows visualizations of earth surface temperature for January and July. Color in the
legend and the visualizations.
Worksheet 3 shows the seasonal temperature change, or July minus January in worksheet
#2. Color in the legend and the visualization.
Insolation and surface temperature
Click on each visualization below to view a larger version
Insolation (worksheet 1)
Surface Temperature (worksheet 2)
Seasonal temperature difference
Change in Surface Temperature from January to July (worksheet 3)
The following visualization was achieved by subtracting January from July. Click on it to see a
larger version.
Understanding seasonal temperature difference
The worksheet 3 visualization has a lot of information in it. Let's look at it a litte more closely.
Think about each visualization as being made up of little cells. Each cell is assigned a color. The
color corresponds with a value, in this case, temperature. The red areas represent a positive value,
meaning that the temperature is warmer in July than in January. The blue areas represent a
negative value, meaning that the temperature is cooler in July than in January. This type of
visualization is useful to understand how areas change over time. What does a very dark red
color mean? What does a color very close to white mean? Compare this figure to the 'Normal
Annual Range in Temperature' figure on page 17 of Goodes World Atlas.
Here is another way to understand what this visualization is showing. It was created by
overlaying the January and July surface temperature visualizations (worksheet 2) and subtracting
them. So, for given the following cell values:
Location
January
Temperature
July
Temperature
Difference
Color
San Francisco
15
30
+15
red
Tierra del Fuego
10
-5
-15
blue
The negative value for Tierra del Fuego would indicate that January is warmer than July, while
a positive value for San Francisco indicates that July is warmer than January. Basically, you are
looking at the net difference, but the value (positive or negative) tells you which month is
warmer.
Answer these questions using Worksheets 1, 2 & 3
All answers must be in complete sentences
Insolation (Worksheet 1)
6. (3 pts) The hemisphere getting the most energy is the one experiencing summer. Which
hemisphere is experiencing summer in January? Which hemisphere is experiencing summer in
July?
7. (3 pts) Why are the incoming solar energy visualizations for January and July nearly opposite
of each other?
8. (3 pts) Notice that the two hemispheres do not get equal amounts of energy. During which
month does the hemisphere experiencing summer get the most energy? Is it the Southern
Hemisphere in January or the Northern Hemisphere in July?
9. (3 pts) Why do you think that the summer hemisphere you selected in question 8 is getting
more energy? (hint: refer to lecture from week 1).
Surface Temperature (Worksheet 2)
10. (3 pts) Why are the temperature patterns (worksheet 2) so much more complex that the
incoming solar energy patterns (worksheet 1)?
11. (3 pts) Look at the visualization of earth surface temperature for January and July (worksheet
2). Overall, which month is warmer? (Hint: look at the extremes -- where are the coldest areas?
Where are the hottest areas?)
Seasonal temperature difference (Worksheet 3)
Notice that the month with the highest temperature in #11 is the month getting less energy in
#8. Why is that? In this section you will explore this question by looking at differences in
temperature. In the final section you will put it all together.
12. (5 pts) The visualization in worksheet 3 of seasonal difference is calculated by subtracting
the January temperature from the July temperature. Given the January and July temperatures for
the following cities, calculate the seasonal difference (July - January). What is the temperature
difference and, based on the color bar in worksheet #3, what color would each be?
City
July temp (C)
January temp (C)
Monterey, CA
20
18
Bismarck, ND
21
-12
Honolulu, HI
22
24
Christchurch,
NZ
8
20
Sydney, Aust.
10
25
Difference (C) Color
13. (5 pts) Why is the red mainly in the north and the blue mainly in the south (e.g. what do the
colors red and blue mean in this visualization)?
14. (3 pts) Contrast the changes on land with the changes on water. Which changes more, Land
or Water?
15. (3 pts) Using the land mass distribution graph in worksheet 3, which hemisphere has the most
land, the Northern or the Southern?
Putting it all together
16. (20 pts) Look at the surface temperature by hemisphere graph in Worksheet 3. Why does the
Northern hemisphere have a hotter summer and a colder winter than the Southern
Hemisphere? Write at least two paragraphs justifying your answer citing evidence from the
worksheets and graphics.