Geography 101 Lab 1 Earth Sun Geometry and Insolation ...

Geography 101 Lab 1 Earth Sun Geometry and Insolation ? Practice Questions

You should be able to calculate the noon sun angle of a place during the solstices and equinoxes.

1. If you are in Sydney, Australia and the date is September 22, what is the declination of the sun? 0?, the Equator. The only thing that matters is the date. Where you are is irrelevant.

2. It's June 21 and you're on vacation checking out the beaches just north of Mazatlan, Mexico, at latitude 23.5? N. What is the declination of the sun? 23.5?N. The date is the only thing that matters. Where you are is irrelevant.

3. It's June 21 and you're in New York City, NY (40.5? N). What is the noon sun angle in New York?

Latitude = 40.5?N

Declination = 23.5?N Zenith angle = 40.5?N ? 23.5?N = 17?

Noon sun angle = 90? ? 17? = 73?

4. It's March 23 and you're in Paris, France (49? N). What is the noon sun angle in Paris?

Latitude = 49?N

Declination = 0?

Zenith angle = 49?N ? 0? = 49?

Noon sun angle = 90? ? 49? = 41?

5. It's June 21 and you're in some un-named location in Antarctica, latitude 66.5? S. What is the noon sun angle at

your location?

Latitude = 65.5?S

Declination = 23.5?N Zenith angle = 65.5?S + 23.5?N = 89?

Noon sun angle = 90? ? 89? = 1?

6. It's September 23 and you're in Suva, Fiji (18? S). What is the noon sun angle?

Latitude = 18?S

Declination = 0?

Zenith angle 18?S ? 0? = 18?

Noon sun angle = 90? ? 18? = 72?

7. Of all the cities on the South America map below, which city will have the smallest change in noon sun angle throughout the year, and which city will have the largest change in noon sun angle throughout the year? Why? Smallest change in noon sun angle: city closest to the Equator ? Quito. Largest change in noon sun angle: city at the highest latitude ? Buenos Aires and Montevideo (Tierra del Fuego will have a large change, but it's not a city)

You should be able to explain how sun angle and insolation intensity change with latitude and season.

8. In which of the four cities listed below and shown on the South America map below, will a beam of sunlight be

dispersed over the smallest surface area at noon on June 21? On December 22? On March 23? Why?

Brasilia

Cayenne

Asuncion

Quito

The city with the highest sun angle; as sun angle increases, sunlight becomes more concentrated. The city

with the highest sun angle will be the one closest to the declination.

June 21 declination =23.5?N ? Cayenne

December 22 declination = 23.5?S ?Asuncion

March 23 declination = 0? ? Quito

9. Which of the four locations in questions 3, 4, 5, and 6 6 (New York, Paris, Antarctica, Suva) will receive the most intense insolation on the dates listed? Why? New York City; it has the highest sun angle. As sun angle increases, sunlight is more concentrated and intensity increases.

10. How will the noon sun angle change traveling from London (51.5? N) to Accra, Ghana (5.5? N), on June 21? How will the insolation intensity change traveling from London to Accra on June 21? Noon sun angle in London is 62? (51.5?N ? 23.5?N = 28?; 90? ? 28? = 62?) Noon sun angle in Accra is 72? (23.5?N ? 5.5?N = 18?; 90? ? 18? = 72?) Traveling south, the noon sun angle will gradually increase from 62? in London reaching 90? at latitude 23.5?N, and then gradually decrease to 72? in Accra. As the sun angle increases, the insolation intensity will also increase peaking at 23.5 ?N. Continuing south from 23.5 ?N to Accra, sunlight intensity will gradually decrease.

11. How will the noon sun angle change traveling from London (51.5? N) to Accra, Ghana (5.5? N), on December 21? Where (at what latitude) between London and Accra will insolation be most intense? Noon sun angle in London is 15? (51.5?N + 23.5?S = 75?; 90? ? 75? = 15?) Noon sun angle in Accra is 61? (5.5?N + 23.5?S = 29?; 90? ? 29? = 61?) Traveling south from London, the noon sun angle will gradually increase. Accra will have the most intense insolation because it has the highest sun angle.

12. What is the noon sun angle in Honolulu, Hawaii (21.5? N) on the following dates:

Declination zenith angle

noon sun angle

March 23

0?

21.5?

68.5?

June 21

23.5?N

2?

88?

September 23

0?

21.5?

68.5?

December 22

23.5?S

45?

45?

Describe the associated change in insolation intensity with season in Honolulu.

June has the highest insolation intensity (sun angles are highest). After June, insolation intensity decreases

reaching its lowest value in December after which intensity gradually increases back to its highest value in June.

13. What is the noon sun angle in London (51.5N) on the following dates:

Declination zenith angle

noon sun angle

March 23

0?

51.5?

38.5?

June 21

23.5?N

28?

62?

September 23

0?

51.5?

38.5?

December 22

23.5?S

75?

15?

Describe the associated change in insolation intensity with season in London.

June has the highest insolation intensity (sun angles are highest). After June, insolation intensity decreases

reaching its lowest value in December after which intensity gradually increases back to its highest value in June.

14. Compare the change in noon sun angle and insolation intensity with season in Honolulu and London. Insolation intensity reaches its highest value in June and its lowest value in December for both cities, so the direction of change throughout the year is similar. The difference is that London has a larger change in intensity throughout the year than Honolulu due to the fact that London has a larger change in sun angle throughout the year than Honolulu (47? for London and 43? for Honolulu).

You should be able to explain how day length changes with latitude and season.

15. If the date is September 23, which of the four locations in questions 3, 4, 5, and 6 (New York, Paris, Antarctica, Suva) will have the most hours of sunlight (longest day)? They will all have the same day length; 12 hours of sunlight.

16. If the date is December 22, which of the four locations in questions 3, 4, 5, and 6 (New York, Paris, Antarctica, Suva) will have the fewest hours of sunlight (shortest day)? The city farthest from the South Pole (90?S); Paris.

17. Which of the following four cities, shown on the South America map below, will have the longest day (most

hours of sunlight) on June 21? Why?

Caracas

Quito

La Paz

Santiago

The city farthest north - Caracas. The northern hemisphere has longer days than the southern hemisphere in

June with the North Pole (90?N) getting 24 hours of sunlight.

18. Which of the following four cities, shown on the South America map below, will have the longest day on

December 22? Why?

Georgetown

Lima

Asuncion

Montevideo

The city farthest south ? Montevideo. The southern hemisphere has longer days than the northern

hemisphere in December with the South Pole (90?S) getting 24 hours of sunlight.

19. Of all the cities on the South America map below, which city will have the smallest change in day length throughout the year, and which city will have the largest change in day length throughout the year? Why? Quito. The city with the smallest change in day length throughout the year will be the one closest to the Equator ? the Equator has 12 hours of sunlight all year round.

20. Describe how day length (hours of sunlight) will change traveling from Caracas to Tierra del Fuego, shown on the South America map), on June 21 and on December 22. June 21: Caracas will have slightly more than 12 hours of daylight because it's north of the Equator, which has 12 hours of sunlight. Traveling south, the hours of sunlight will decrease with Tierra del Fuego having the shortest days.

December 22: Caracas will have slightly less than 12 hours of daylight because it's north of the Equator, which has 12 hours of sunlight. Traveling south, the hours of sunlight will increase with Tierra del Fuego having the longest days.

You should be able to explain how sun angle, insolation intensity, and day length affect temperature.

21. Which of the four locations in questions 3, 4, 5, and 6 6 (New York, Paris, Antarctica, Suva) should be hottest

on the dates listed? Why?

March 23

June 21

September 23

December 22

March 23 and September 23: Suva because it's closest to the Equator, which is where sun angles are highest.

December 22: Suva because it has higher sun angles and longer days than New York and Paris. Antarctica does

have longer days than Suva, but the sun angles are very low, resulting in colder temperatures in Antarctica.

June 21: New York because it has the highest sun angles. Paris has longer days than New York, but lower sun

angles, so New York should be warmest.

22. You're trying to decide where to vacation over semester break (end of December) and have a choice of traveling to either Porto Alegre, Brazil (30? S) or Cairo, Egypt (30? N). Your primary concern is warm temperatures. Which place should be warmer based on earth-sun relations? Why? Porto Alegre should be warmer. It is closer to the declination so it has higher sun angles than Cairo. Porto Alegre also has longer days than Cairo because it's in the southern hemisphere.

23. If you lived in Honolulu, Hawaii (21.5? N) and stepped outside at noon on the four dates listed below, in what

direction (north, south or directly overhead) would you look to see the sun?

March 23

June 21

September 23

December 22

Will the direction you look have an impact on the temperature in Honolulu? If so, explain why, if not, state

what factors would impact temperature in Honolulu.

March 23 and September 23: look south because the declination is 0? while Honolulu is at 21.5?N

June 21: look north because the declination is 23.5?N while Honolulu is at 21.5?N.

December 22: look south because the declination is 23.5S?N while Honolulu is at 21.5?N

The direction you look (N or S) doesn't matter. The sun angle is what matters most along with day length.

24. Of all the cities on the South America map below, which city should have the smallest change in temperature throughout the year, and which city should have the largest change in temperature throughout the year? Why? Quito should have the smallest change in temperature. Day length will be a constant 12 hours every day of the year and sun angles will be high all year round. Quito should, therefore, have warm temperatures all year round. Buenos Aires and Montevideo should have the largest change in temperature throughout the year (provided you don't include Tierra del Fuego, which isn't a city) because they have the largest change in noon sun angle and the largest change in day length throughout the year.

Tierra del Fuego

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