Meteorology 3000- Mountain Weather and Climate

Assignment 4. Due September 21. 10 points You may turn this assignment in on paper (be neat!) or email. To receive full credit, don't just write down an answer- show intermediate steps.

1. (4 points) Refer to Appendix A and B for this problem. Using a sling psychrometer (the name of the instrument with the pair of web/dry bulb thermomemters), you find that:

a. the dry bulb temperature is 25C and the web bulb temperature is 10C. What is the relative humidity in percent?
b. you hear on the news that the (dry bulb) temperature is 50F and that the relative humidity is 25%. What must the wet bulb temperature be in F and C?
c. you are standing at the top of a mountain peak at 0C surrounded by fog. The saturation vapor pressure (mb) at 0C is 6.1 mb. What is the vapor pressure (mb)?
d. same situation as in (c) but the fog dissipates. The relative humidity has dropped to 70% but the vapor pressure has remain unchanged from the value determined in (c). Using Figure A.1, estimate roughly what the temperature must have increased to.

2. (4 points) Refer to Table 4.1 (Standard Atmosphere)

a. Calculate the lapse rate (rate of decrease of temperature with height in C/km) in the layer between sea level and 850 mb. Between 700 mb and 500 mb.
b. Are the lapse rates calculated in (a) greater than, less than, or equal to the dry adiabatic lapse rate? Assuming that the atmosphere remains unsaturated, are the layers in (a) stable, neutral, or unstable?
c. A parcel of air originally at 900 mb for the situation in (a-c) is lifted up 10 mb. Will it continue to rise, stay at the same level, or sink back towards its original level? Why? The parcel is depressed 10 mb from 900 mb. Will it continue to sink, stay at the same level, or rise back towards its original level? Why?
d. The temperature at sea level on a particular day is 20C. Assuming that the lapse rate is as you determined in (a), what is the height (in both feet and meters) of the freezing level in this situation?

3. (1 point) Refer to Table 4.1 the standard atmosphere. You are on top of a mountain at an elevation of 5570 m.

a. What is the pressure in mb? in pa, in kilopascals, in inches of mercury?
b. How long (roughly) will it take for you to boil water? Why does it take longer to boil the water at this elevation compared to sea level?

4. (1 point) I am standing in a very cold environment at night without a hat (oh no!). The winds are calm. I am not wet. I am losing 10 Watts/kg of net longwave radiation more than my body can generate metabolically. The specific heat of my body is 3000 J/(kg C). My body temperature is 37C. How long (min) will it take for my body to cool to 30C? Explain your reasoning and discuss the magnitude of each term of the heat budget of the body.