Radiation, Temperature, and Phase Changes

Instructions:

Answer all of the questions completely listing appropriate units and equations on all numerical answers and answer non-numerical questions with complete sentences. Please write neatly when completing this assignment – if we can’t read your answer you will not get credit for it. If you require additional space to show more work, attach an extra page and clearly indicate the question it addresses.

1) To understand the weather it is necessary to visualize spatial changes in atmospheric properties. One way atmospheric scientists do this is by looking at contour maps of different atmospheric variables. Look at the graph below. This is a plot of average daily insolation vs latitude and time of the year. 

1. What is the Latitude of Boulder, CO

2. What is the average daily insolution in Bouler, CO on Julian Day 50? Approximately what month and day does this correspond to?

3. Approximately what is the average daily insolation in Boulder, CO in June.

4. What caused the insolation to change in this way from Julian Day 50 to June? Looking for more than “more/less sunlight” or “seasons.”

Say you wish to live in a place where you get to experience one single full day of NO sunlight (but NO more), what latitude would you move to and what Julian day (or date) would that occur? 

Where specifically might you move to so that you can experience this? Look at/near the equator on this plot and use this to determine which hemisphere receives OVERALL more yearly solar insolation? Give at LEAST two reasons why and defend your arguments.

2) On the surface temperature map below, draw and label contour lines (isotherms) every 10°F on the map of surface air temperature from 00Z 12 December 2015 given below.

What is the valid date and time of this map in Mountain Standard Time (MST)?

Mark and label the location of the largest and smallest temperature gradients on this map. How did you determine this when looking at your contour map? Assuming no clouds, describe how the temperature contours might change between 00Z and 12Z. Explain physically what is happening that would cause these shifts. Now, what if an enormous cloud forms over the state of Iowa at 6Z and sticks around until 12Z, what would happen to the surface temperatures in Iowa? How might this look as a contour at 12Z?

3) As water changes phase in the atmosphere, energy is either released from the water to the air or taken from the air by the water. This energy exchange is important for many atmospheric processes. First, consider 1 kg of air that contains 15 g of water vapor. If all of this water vapor condenses, will the air temperature increase, decrease, or remain constant? Explain why.

- Using the latent heat factors (L) given in the chapter 3 lecture notes calculate how much latent heat is associated with 15 g of water vapor condensing into liquid and liquid freezing into ice respectively.

- Using the first law of thermodynamics from the chapter 3 lecture notes, calculate how much the temperature of 1 kg of air will change due to the latent heat released by 15 g of water vapor condensing into liquid and liquid freezing into ice respectively. Assume constant air pressure.

- Provide a physical explanation for this difference in energy released from vapor condensing into liquid and liquid freezing into ice.

4) A summer thunderstorm passing over Boulder, CO causes 2 cm of rain to fall in 30 minutes. The base of the thunderstorm is 1.5 km above the ground and as the rain falls out of the cloud base it begins to evaporate. Using the first law of thermodynamics and the latent heat factors given in the chapter 3 lecture notes, calculate how much the air temperature will change as a result of this amount of rain evaporating as it falls through the 1.5 km depth of atmosphere. You may assume that the air pressure remains constant during this thunderstorm. Hint: The mass of air involved is 1500 kg and the mass of rain is 20 kg.