Reference no: EM132194500

Question: Intensity of sunlight worksheet

In this worksheet we are going to calculate how intensity of sunlight varies with distance from the Sun and location on Earth. The results will allow us to determine whether Earth's orbital eccentricity or axial tilt plays a more important role in the seasons.

1. Earth orbits the Sun in an elliptical orbit. At perihelion Earth is 1.47×108km from the Sun, at aphelion it is 1.52×108km. The Sun's luminosity is 3.85×1026W. Calculate the intensity of sunlight at Earth's distance at perihelion and aphelion. Give your answers in W/m2to 3 significant figures.

2. By what factor does intensity of sunlight vary due to Earth's orbital eccentricity, i.e. what is the ratio of the maximum to the minimum intensity?

We have previously calculated the intensity of sunlight in Calgary at noon on summer solstice. Now we will do so for winter solstice.

3. Sketch a diagram showing how sunlight strikes Earth's surface in Calgary at noon on winter solstice. Indicate the values of all the relevant angles.

Astronomy 1301 Dr. Raphael Slawinski

4. How high above the horizon is the Sun in Calgary at noon on winter solstice? Give your answer in degrees.

5. Calculate the intensity of sunlight in Calgary at noon on winter solstice. Use the average value of the intensity of sunlight at Earth's distance, i.e. the "solar constant" calculated in class.

6. By what factor does the intensity of sunlight in Calgary vary over seasonal cycle, i.e. what is the ratio of the maximum to the minimum intensity?

7. Based on your answers to questions 2 and 6, does Earth's orbital eccentricity or axial tilt play a more important role in the seasons?