1. Lecture 3 Vertical Structure of the Atmosphere

2. Average Vertical Temperature profile

3. Atmospheric Layers Troposphere On average, temperature decreases with height On average, temperature decreases with heightStratosphere On average, temperature increases with height On average, temperature increases with heightMesosphereThermosphere

4. Lapse Rate Lapse rate is rate that temperature decreases with height

5. Soundings Actual vertical temperature profiles are called soundings A sounding is obtained using an instrument package called a radiosonde Radiosondes are carried aloft using balloons filled with hydrogen or helium

6. Radiosonde http://www.srh.noaa.go v/mob/balloon.shtml

7. Application: Reduction to Sea Level (See Ahrens, Ch. 6) Surface pressure here proportional to weight of this column of air Surface pressure also called station pressure (if there is a weather station there!)

8. Math Obtained by integrating the hydrostatic equation from the surface to top of atmosphere.

9. Deficiencies of Surface Pressure Spatial variations in surface pressure mainly due to topography, not meteorology

10. 900 950 1000 1050 Height contours on topographic map Units: m It’s a mountain!

11. Put a bunch of barometers on the mountain.

12. Surface pressure (approximately) 885 890 895 900 Isobar pattern looks just like height-contour pattern! Units: hPa

13. “Reduction to Sea Level” Sea Level Surface pressure here is proportional to weight of this column of air Let T = sfc. temp. (12-hour avg.) For sea level pressure add weight of isothermal column of air temp = T.

14. Pressure as Vertical Coordinate Pressure is a 1-1 function of height i.e., a given pressure occurs at a unique height i.e., a given pressure occurs at a unique height Thus, the pressure can be used to specify the vertical position of a point

15. Given p At what height is the pressure equal to p?

16. Pressure Surfaces Let the pressure, p 1, be given. At a given instant, consider all points (x, y, z) where p = p 1 This set of points defines a surface

17. x z p = p 1 x1x1 x2x2 z(x 1 ) z(x 2 )

18. Height Contours Heights indicated in dekameters (dam) 1dam = 10m

19. Two Pressure Surfaces z p = p 1 p = p 2 z2z2 z1z1 z 2 – z 1

20. Thickness z 2 – z 1 is called the thickness z 2 – z 1 is called the thickness of the layer Hypsometric equation  thickness proportional to mean temperature of layer

21. Thickness Gradients z p = p 1 p = p 2 Small thickness Large thickness Cold warm

22. Exercise Suppose that the mean temperature between 1000 hPa and 500 hPa is -10  C. Calculate the thickness (in dam)

23. Repeat, for T = -20  C

24. Thickness Maps Thickness Maps