Insolation

1. Insolation • INcoming SOLar radiATION • Strength is dependent on • Angle of insolation • Duration of insolation • Type of surface receiving the insolation

2. EM Energy Interactions in Environment • Refracted – bent as pass through • Reflected – bounced off • Scattered – refracted or reflected in various directions • Transmitted – passed through • Absorbed – taken into

4. Electromagnetic Spectrum • Organisms vary in their ability to sense different parts of the spectrum.

7. Angle of Insolation • A measure of how high the Sun is in the sky • The higher the Sun, the more direct the Sun’s rays. • The more direct the rays, the greater the amount of insolation. • What time of day is insolation the greatest?

8. Angle changes throughout the year • In Northern Hemisphere – Rays are most direct in summer. • Direct rays strike the Tropic of Cancer on the Summer Solstice. • What time of the year is insolation the greatest in the S. Hemisphere?

9. As you travel poleward, the angle of insolation decreases. • How does this affect global heating? • How do temperatures compare between the tropics and the poles? • This difference in heating drives the Earth’s weather systems.

10. Effect of Angle of Insolation Same amount of incoming energy. The more direct the angle the more ‘concentrated’ the energy

11. Equator 30 ° 45° Poles Relative amount of incoming energy __________ _____________________________ _____ ______ Greater the angle, the less ‘concentrated’ the energy

12. Intensity of insolation depends upon: • Latitude • Farther you are from the equator the less energy reaches you

13. Same area covered Different amounts of energy Less energy: colder More energy: warmer Less energy: colder

14. Season • More energy reaches you in summer than in winter

16. Monthly Insolation Values

17. Annually, energy transfers from the Equator to the Poles on a global scale. Watch how this happens over a year!....

18. JANUARY -10.0 0.8 11.6 22.4 33.2 (oC )

19. FEBRUARY

20. MARCH

21. APRIL

22. MAY

23. JUNE

24. JULY

25. AUGUST

26. SEPTEMBER

27. OCTOBER

28. NOVEMBER

29. DECEMBER

30. JANUARY

31. Duration of Insolation • This is the length of daylight in a day. • The longer the amount of daylight, the greater the amount of insolation. • What time of year has the longest hours of daylight?

32. Length of Daylight

33. Absorption of Insolation • Absorption depends on texture and color. • The rougher the texture, the more absorption takes place. • Darker colors absorb insolation at a greater rate the lighter colors. • Which absorbs more? A blacktop parking lot or a snowy field?

34. Since dark colors absorb heat radiation then light colors reflect radiation. • Light energy reflected from a surface is called albedo. • Surfaces with high albedo reflect a lot of light • For instance, snow has a high albedo. The surface of the moon has a high albedo. A mirror has a high albedo. • Name a type of surface with a low albedo.

35. SURFACE % reflected Dense, dry, clean snow 86-95 Clean sand 37 Ice sheet 26 Grass 25 Decidudous forest 17 Pine forest 14 Ploughed field---moist 14 Swamp 10-14 Albedo of selected surfaces

36. Presence of cloud cover • Clouds absorb and reflect some incoming energy. In the day, less heat will reach the ground • At night, clouds act as blankets to prevent heat from returning to space

37. Effect of Angle of Insolation • More energy reaches the equator than the poles • There is a gain of energy at the equator • There is a loss of energy at the poles • Unequal heating of earth causes giant convection cells to form • Result = global winds

38. Winds and Ocean Currents • The energy of the earth is not static • It can be transferred either by winds or ocean currents. • Most of the insolation reaches the earth and heats up the oceans and the seas • Temperatures of areas near the coast are modified. Example Vancouver and Ottawa

39. Formation of convection cells

40. Warm air rises • Cool air sinks • Convection cells form • Earth is spinning: adds another factor in formation of global winds • Coriolis effect

42. Coriolis Effect • objects moving in the northern hemisphere are deflected toward the rightof their direction of motion • Objects moving in the southern hemisphere are deflected toward the leftof their direction of motion

43. Resulting wind pattern is called3-celled model of global air circualtion

45. Review • What is insolation? • What are 3 things that affect insolation? • What time of day is insolation the greatest? • What time if year is insolation the greatest? • How does latitude affect insolation?

46. Review • How does color affect absorption of radiation? • What is albedo? • Name a surface that has high albedo.

47. Lag Time of Maximum Heat • The maximum heat produced by the Sun does not occur at the same time as maximum insolation • This is due to the time it takes for the object or surface to heat up.

48. Dec 21 June 21

49. So, even though maximum insolation is in June, the warmest month is July/August due to the time it takes for the atmosphere to warm to the max. • The same is true for daily heating. Even though the maximum insolation is at noon, the hottest time of day is late afternoon

50. The Greenhouse Effect • The greenhouse effect is the rise in temperature of Earth’s atmosphere. • This rise is caused by certain gases.(Water vapor, carbon dioxide, nitrous oxide, and methane, for example)