Grace Neylan

Mr. DeSain

Period 7

June 7, 2011

Chapter 6 Insolation and the Seasons

Insolation or incoming solar radiation is the part of the sun’s output of electromagnetic radiation that is received by the Earth. In other words it is the amount of sunlight that comes to Earth’s surface. Without the energy that we get from the sun the Earth would be much different, it would be much colder, and the ocean currents water cycle and wind patterns would be different. Without insolation there would be no atmospheric gases on Earth and no water.

As seen in the picture not 100% of the insolation coming to Earth actually reaches the Earth’s surface, about half of the insolation reaches Earth. The insolation can be either reflected, refracted, or absorbed (RAR, ARR, RRA). One example of something that can reflect, refract, or absorb the insolation is a cloud. Clouds can reflect insolation back into space and reflect it towards Earth’s surface.

Along with insolation ultraviolet waves can reach Earth. Ultraviolet waves can reach Earth easier than in past years due to the reduced amount of ozone in the upper atmosphere.

After insolation reflects off of Earth’s surface it mostly stays inside of Earth’s atmosphere, this causing the greenhouse effect. This happens because greenhouse gases such as carbon dioxide, water vapor, methane, and other gases makes up the Earth’s surface radiation. This causes heating and can be called a heating “blanket”, this “blanket” keeps Earth’s surface about 59˚F warmer.

With the heating of land and water there is a difference in the amount of time it takes to heat them. Land heats faster than water and that is due to the fact that water’s specific heat is higher meaning that more time is needed to heat the water. Variations in insolation cause the seasons because of either the strength (intensity) or the length of time (duration). The highest angle of insolation is 90˚ and that causes the greatest amount of insolation going to one spot. As the angle decreases from 90˚ to 0˚ the amount of insolation does not change but it is the amount of area that is being heated that changes, causes the temperature to not be as high as the angle of 90˚. Noon (solar noon) is when the sun is highest in the sky and the greatest amount of insolation, but it is not the hottest part of the day. The hottest part of the day is sometime around mid- afternoon.

The insolation that is received from sunrise to sunset is called the duration of insolation. Duration of insolation corresponds with the number of hours of sunlight in a day. In the United States the day that has the longest insolation is June 21 and the day with the shortest is December 21. On an equinox the amount of insolation is about 12 hours because the sunrises exactly east and the dates of the equinoxes are March 21 and September 23.

1. The electromagnetic radiation that the Earth’s surface receives is?

a. global warming

b. insolation

c. wavelength

d. ozone

2. At which angle of insolation is the insolation the greatest?

a. 65˚

b. 0˚

c. 90 ˚

d. 110˚

3. Which statement is true about how the Earth would be without insolation?

a. The Earth would be warmer

b. There would be more water on the Earth’s surface

c. There would be more oxygen

d. No one could live on Earth and it would be colder

4. The equinoxes are: a. ______

b. ______

5. The day with the longest amount of insolation is:

a. ______

6. The day with the shortest amount of insolation is:

a. ______

7. What is the main reason that Rochester, New York is warmer in June than in December

a. The amount of insolation is greater in June

b. Earth is farther from the sun

c. Earth is closer to the sun

d. The moon is closer to Earth

8. Not 100% of insolation reaches earth, which of these reasons for that is false?

a. Reflection

b. Collection c. Absorption

d. Refraction

9. What time of the day is it warmest?

a. Mid- afternoon

b. Early morning

c. Noon

d. Sunset

10. What is the name for the time of the day when the sun is highest in the sky?

a.______

11. Name three greenhouse gases

a. ______

b. ______

c. ______Answers:

1. B. 2.C. 3.D. 4. March 21, September 23 5. June 21 6. December 21

7. A. 8. B. 9. A. 10. Solar Noon 11. Methane, Carbon Dioxide, Water Vapor