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Chapter 5 Global Temperature (Continued)

Chapter 5 Global Temperature (Continued). Lecture 12 2 February, 2005. Land versus ocean differences. Clouds and Temperature Changes. Clouds trap net radiation in lower troposphere. Clouds reduce surface insolation. Little seasonal change in ocean surface temp.

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Chapter 5 Global Temperature (Continued)

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  1. Chapter 5Global Temperature (Continued) • Lecture 12 • 2 February, 2005

  2. Land versus ocean differences

  3. Clouds and Temperature Changes Clouds trap net radiation in lower troposphere Clouds reduce surface insolation

  4. Little seasonal change in ocean surface temp warmest ocean waters occur in the western tropical Pacific notice the changes in sea ice in the northern and southern hemispheres

  5. Difference between January & July focus on differences between the northern and southern hemispheres why should the seasonality in N. America be smaller than in Asia at similar latitudes? why should northern Siberia have the greatest seasonality?

  6. Seasonal Temperature Range in Siberia the seasonality in northern Siberia is extreme for several reasons: continentality solar angles clear, dry air with little cloud cover (think of albedo & greenhouse cloud effects) Verkhoyansk, Russia has a 105 °C min-max range!

  7. Marine and Continental Climates San Francisco CA Witchita KS

  8. Marine and Continental Climates Trondheim Norway Verkhoyansk Russia

  9. Gulf Stream & Temperature in Western Europe think of the Gulf Stream as a gigantic river of warm water in the Atlantic (moving about 6.4 kph/4 mph) the amount of water flow in this ‘river’ is ~100 sverdrups (100 million cubic meters per second) the Gulf Stream was named and partly discovered by Benjamin Franklin Not exactly the whole story…

  10. The Gulf Stream

  11. The Gulf Stream and Temperatures in Western Europe water-to-land heat transfers are accomplished via latent heat transfers and direct sensible heating of air overlying warm water the Gulf Stream largely explains why Iceland is mostly green, even though it sits just below the Arctic Circle variations in the Gulf Stream have had huge implications for human societies, such as allowing the Vikings to reach eastern Canada and the little Ice Age Movie: ‘The Day After Tomorrow’

  12. California current & temperatures in coastal California water can directly warm or cool nearby land masses - compare California’s cool coastal Mediterranean climate with the warm coastal climate of Italy

  13. Air temperature patterns some definitions isotherm - a line connecting points of equal temperature - analogous to a line on a topo map connecting points of equal elevation thermal equator - a line connecting all points of highest average temperature

  14. notice the thermal equator over land notice the influence of large mountain ranges

  15. see how isotherms shift poleward over continental interiors? where would the hottest places be? why?

  16. Show energy budget animation

  17. Wind chill Correlates cold and wind speed Heat index Correlates heat and humidity Air Temperature and the Human Body

  18. Wind Chill Table

  19. Heat Index Table Figure 2

  20. Chapter 6 Atmospheric and Oceanic Circulation Concepts in this chapter air pressure winds (global, regional, and local) global circulation systems four driving forces in the atmosphere primary high and low pressure areas in the atmosphere upper air circulation ocean currents & circulation

  21. Air Pressure “We live submerged at the bottom of an ocean of the element air.” -Evangelista Torricelli

  22. Air pressure recall that air pressure is force per unit area

  23. Ideal Gas Law P V = n R T where R is a constant Pressure*Volume = Moles*constant*Temperature • With Moles of air constant, Pressure increases • as Volume decreases (Temperature constant) • as Temperatureincreases (constant Volume)

  24. Ideal Gas Law PV = nRT Pressure*Volume = Moles*constant*Temperature Figure credit: http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/circulation/air_pressure_p_1.html I. II. III. I. pressure increases if # molecules increases (constant volume) II. pressure increases if volume decreases (constant temperature) III. pressure increases if temperature increases (constant volume)

  25. a quick and dirty estimate of air pressure at the surface 1. define pressure: force per unit area 2. force = mass*acceleration due to gravity (F = m g) 3. mass of the atmosphere = 5x1018 kg gravitational acceleration = 9.81 m s-2 4. surface area of Earth = 4pR2 = 4p (6,400km)2 = 5x1014 square meters 5. plug it all in …. Pressure = F / A = m g /A = 5x1018 kg * 9.81 m s-2 / 5x1014 m2 ~ 100,000 kg /(m s2) Newtons per m2 (Pascal) ~ 1000 millebar (mb)

  26. sea level pressure = 1013 mb = 101.3 kPa = 14.5 lbs/sq. in = 29.92” mercury = 760 mm mercury = 1 atmosphere

  27. Barometer the weight of air literally pushes mercury up the column what would the column’s height be on top of Mt. Everest? elevation is ~8 km ~ 75% of air is below -> 0.25 * 29.92 in ~ 7.5 in

  28. to calculate atmospheric pressure (in mb) by height (Z): P(Z) = 1014*[1-0.0226*Z]^5.26 Pressure in the Atmosphere and Ocean to calculate water pressure (in mb) by depth (D, in m): P(D) = 100*D even though gravity is pulling on both air and water, air is compressible (water is not)

  29. Scuba Diving & Pressure rule of thumb in scuba diving: Each 10 m (33 ft) increase in depth increases the pressure on every square inch of your body by 1 atmosphere Dive to 30 m, you have 4 atmospheres of pressure pushing on you (3 ocean + 1 atmos)

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