Earth s Environmental System: Climate V2100. Midterm Exam. Wednesday March 12, 2003

Transcription

1 Earth s Environmental System: Climate V2100 Midterm Exam Wednesday March 12, 2003 Please put your name at the top of each page If you sketch something, make it big and clear and label your axes Explain your reasoning Use the back of exam pages if you require more space Use your time wisely there are five questions worth 20 points each

2 1) (20 points) Consider the following scenario: We are following an air parcel from San Francisco on the west coast, over the Sierra Nevada mountains and into Colorado. The wind is blowing from west to east. a) Use the provided section with distance on the x axis and height on the y axis. The height of the mountain chain in the middle of the graph is 3000 m. Indicate on the graph at various points the air temperature and dew point temperature of the air parcel. The conditions at ground level in San Francisco are 18 o C with a dew point of 13 o C. b) At which height will clouds form (use round number lapse rates)? c) What are the weather conditions, temperature and dew point at the peak of the mountain? d) What is the temperature and dew point temperature at sea level downwind of the mountain? Is the relative humidity higher or lower compared to San Francisco (don't compute relative humidity exactly just discuss)?

3 2) (20 points) Below is a plot which shows the amount of heat transported by the ocean and atmosphere in the northern hemisphere. a) Describe two ways the ocean transports heat from equator to pole. b) Why is the maximum in oceanic heat transport found at 20 N? c) What atmospheric phenomena is responsible for the large atmospheric heat transport between 30 and 70 N? d) If there were no transport of heat by the atmosphere or ocean, how would the Earth s temperature change at the equator? The poles?

4 3) (20 points) Below you are given the mean winter surface pressure distribution over the North Atlantic Sector. a) Explain why there is a low pressure system over the sub-polar North Atlantic Ocean in winter. b) Sketch the balance of forces that result in surface winds (neglect friction) for the Low pressure system. c) Now considering friction at the surface, indicate the direction of the surface winds on the map. d) Where do we expect rainfall to occur and why?

5 4. (20 points) The diagram below shows the direction of wind along the coast of Somalia (Northern Hemisphere) in January. a) On the diagram indicate the direction of the Ekman transport. b) Do you expect to find upwelling or downwelling near the coast? c) How does this Ekman transport affect the slope of the sea surface and pressure gradient in the upper ocean? d) What is the direction of the resulting geostrophic transport? Somalia Indian Ocean

6 5. (20 points) The ocean surface water in the subtropics (approximately latitude) has a higher salinity than that of the tropical ocean (Equatorial region). Another attribute of the surface salinity pattern is that the surface water of the North and South Atlantic Ocean is saltier than that of their counterparts in the Pacific Ocean. a) Explain how the subtropical to tropical surface salinity difference is consistent with the low latitude Hadley Cell b) Offer a reason that may account for the relatively salty Atlantic. c) Why doesn t the surface salinity of the ocean subtropical regions or that of the Atlantic continuously become saltier?