7.2 What is the normal global distribution pattern of

1. 7.2 What is the normal global distribution pattern of temperature? Part A

2. What is the major factor affecting air temperature? What is the major factor affecting air temperature? Monthly mean temperatures What is the relationship between location and annual mean temperature of the following three places? Insolation. What makes the air temperature vary among latitudes and at different times of a year?

3. What is insolation? The sun is constantly releasing energy in all directions. This energy is known assolar radiation. Space The atmosphere Solar radiation In order to have a better understanding of the issue of global warming, we have to know more about insolation. Solar radiation that is received in the atmosphere or on the earth’s surface is known as insolation. Insolation Earth’s surface Earth’s surface

4. - - What is insolation? Is insolation evenly distributed on the earth? Less insolation More insolation + Average annual insolation over the earth’s surface In general, insolation received ( declines / increases ) with increasing latitude. The distribution of insolation on the earth’s surface is ( even / uneven ).

5. What is insolation? Is insolation evenly distributed on the earth? Why does insolation vary with latitudes? Average annual insolation over the earth’s surface The areas around _______ N and S receive the highest value of insolation. Which areas receive the highest value of insolation?

6. What is insolation? What factors affect insolation received on the earth’s surface? Factors affecting insolation received on the earth’s surface Angle of the sun Duration of daylight The atmosphere Latitude Time of a day Season

7. In Part B, we will discuss the relationship between insolation and air temperature.

9. 1 Angle of the sun The angle of the sun refers to the angle at which sunlight strikes the earth’s surface. Overhead sun When the sun is directly overhead, or when the angle of the sun is 90°, it is known as the overhead sun. How does the angle of the sun affect the intensity of insolation? 90° / Right angle < 90° / Acute angle Smaller Larger High / More intense Low / Less intense

10. 1 Angle of the sun A Latitude In low-latitude regions: The angle of sun is ( smaller / larger ). The insolation concentrates on a ( smaller / larger ) area. Therefore, the insolation is ( weaker / stronger ). (Credit: NASA)

11. 1 Angle of the sun A Latitude In high-latitude regions: The angle of sun is ( smaller / larger ). The insolation concentrates on a ( smaller / larger ) area. Therefore, the insolation is ( weaker / stronger ). (Credit: NASA)

12. 1 Angle of the sun How is the amount of insolation received in this site different in winter? B Time of a day The sun at noon is called themidday sun The angle of sun ( decreases / increases / reaches maximum ) The amount of insolation received will be lower in winter. The angle of sun ( decreases / increases / reaches maximum ) The angle of sun ( decreases / increases / reaches maximum ) The amount of insolation received in a mid-latitude site in the Northern Hemisphere around the spring equinox

13. N S 1 Angle of the sun What is the relationship between the seasons in Hong Kong and insolation? C Season In summer solstice, the overhead sun is located at _______ which is close to Hong Kong. It is the time that Hong Kong receives the ( least / largest ) amount of insolation. In autumnal equinox, the overhead sun is located at the _________. Hong Kong receives less insolation in autumn than in summer. In winter solstice, the overhead sun is located at _________. It is the time that Hong Kong receives the ( least / largest ) amount of insolation. In spring equinox, the overhead sun is located at the Equator. Hong Kong receives ( more / less ) insolation in spring than in winter. Equator Please click above for animation

14. 2 Duration of daylight Is the case in polar areas different? The duration of daylight in equatorial regions is almost 12 hours daily throughout a year. The longer the duration of daylight, the ( less / more ) insolation received. Equator Equator

15. 2 Duration of daylight While in winter, there is no sunlight at all. In polar regions, daylight can last for 24 hours in summer. When does the North Pole receive the largest amount of insolation?

16. 3 The atmosphere The dust particles, gas molecules and clouds in the atmosphere are able to reflect, absorb or scatter solar radiation. Only about 58 units of solar radiation reaches the earth’s surface. How does the atmosphere affect the amount of solar radiation reaching the earth’s surface?

17. Why does the maximum insolation received occur at around N and S but not at the Equator? 3 The atmosphere Maximum insolation received Maximum insolation received Maximum insolation received

18. The climate is drier and there is less cloud cover at around N and S. The earth’s surface receives more insolation, so the amount of insolation is greatest here. Less cloud cover Less cloud cover Dense cloud cover S N 3 The atmosphere Space The atmosphere Insolation is reflected by clouds The amount of cloud cover in the equatorial regions is high. Much of the solar radiation is reflected by clouds. This may reduce the amount of insolation reaching the earth’s surface. 0°