Homework for Chapter 3 - Seasonal and Daily Temperatures

Questions 1 and 2 will be turned in for a grade. Questions 3-10 will be discussed by the discussion groups in class so please look them over before the discussion session.

SHOW ALL WORK , CIRCLE THE CORRECT ANSWER, PLEASE BE NEAT AND STAPLE YOUR HOMEWORK!

ALSO, PLEASE USE A SPREADSHEET FOR ALL GRAPHS

Follow the Problem solving steps discussed in class

1. The solar declination angle d_s is defined as the latitude where the sun angle is 90°. For example, as discussed in class, the solar declination angle on 22 June would be 23.5 degrees N.  For any given day of the year, the solar declination angle is given by:

where F_r is the tilt angle of the earth's axis of rotation, d is the Julian Day of the year, and d_y is the number of days in the year.

Find the solar declination angle on February 1, April 1, June 1, August 1, October 1, and December 1. Make a plot of solar declination angle versus time of the year.

NOTE: The Julian Day is defined as the relative day of the year. For example 15 January corresponds to Julian Day 15. 5 February corresponds to Julian Day (31 + 5) = 36.

2.  The wind chill temperature is the "apparent" temperature that it feels like when one takes into account the effect of wind transporting heat away from your body.  The wind chill temperature can be found with this formula:

where T_windchill is the wind chill temperature, T_skin and T_air are the skin and air temperatures, respectively and M is the wind speed.  M₀ is equal to 2 m/s.

Make your own wind-chill chart.  The vertical axis should be wind speed from 50 m/s to 0 m/s.  The horizontal axis should be air temperature in degrees Celsius.  On this chart, plot wind-chill temperature lines for 0, -10, -20, -30, -40, and -50 degrees Celsius. 

3. Consider two scenarios: (a) The tilt of the Earth decreased to 10°. (b) The tilt of the Earth increased to 40°. How would this change the summer and winter temperatures here at LSC?

4. Where would you expect to experience the smallest variation in temperature from year to year and from month to month? Why?

5. At the top of the earth's atmosphere during the early summer (Northern Hemisphere), above what latitude would you expect to receive the most solar radiation in one day? During the same time of year, where would you expect to receive the most solar radiation at the surface?

6. How would the lag in daily temperature experienced over land compare to the daily temperature lag over water? Draw diagrams for each!!

7. The average temperature in San Fransicso, CA for December, January, and February is 11°C. During the same three-month period the average temperature in Richmond, Virtginia is 4°C. Yet, San Francisco and Richmond have nearly the same yearly total of heating degree-days. Explain why.

8. On a warm summer day, will a city in New Jersey or New Mexico experience a larger diurnal temperature variation? Explain.

9. Suppose peas are planted in Indiana on May 1. If the peas need 1200 growing degree-days before they can be picked, and if the average maximum temperature for May and June in 80°F and the average minimum is 60°F, on about what date will the peas be ready to pick? (Assume a base temperature of 55°F)

EXTRA CREDIT: The temperature of the earths surface is dependent on the net amount of radiation, (net radiative flux), gained or lost at that location.  The net radiative flux in the vertical direction has contributions from four different sources.  Physically describe these four sources.