1. Planetary Energy Budget II
Current News and Weather
Solar Elevation at Noon
Terrestrial Radiation (Long-Wave Energy)
Greenhouse Effect
For Next Class: Read all of Ch. 4

2. Rescue on Nanga Parbat

5. Former Students Chad and Lara Kellogg

6. Former Student Chad Kellogg

9. Snowfall Forecasting Challenges
Quantitative Precipitation Forecast (QPF): How much liquid equivalent precipitation will fall?
Numerical models continue to have major challenges with QPF
Depends on storm track, orographic effects, instability, etc.
Precipitation Type: What form will the precipitation take?
All snow? Snow and sleet? Snow, sleet, freezing rain? All freezing rain?
Snow-to-Liquid Ratios (SLRs): What will the density of the snow be?
Can be highly variable, from 5:1 (5” of snow out of 1” liquid) to higher than 40:1 (40” of snow out of 1” of snow)
Higher SLRs for colder NW flow events, lower for warmer Gulf lows

13. Solar Elevation at Noon
Figure 2.18

14. Solar Elevation at Noon (SEN)
SEN is the angle of the noon sun above the horizon
SEN = 90˚ - ArcDistance
ArcDistance = number of degrees of latitude between location of interest and sun’s noontime vertical rays
If the latitude of location of interest and sun are in opposite hemispheres, add to get ArcDistance
If they are in the same hemisphere, subtract from the larger of the two values

15. SEN Example What is the SEN on June 21 for Boone (36 N)
SEN = 90 – ArcDistance
Where are the sun’s noontime vertical rays?
ArcDistance = 36 – 23.5
ArcDistance = 12.5
SEN = 90 – 12.5
SEN = 77.5˚

16. SEN Exercises
What is SEN in Punta Arenas (53º S) on June 21? December 21?
What is SEN in Cayembe, Ecuador (0º) on June 21? March 21?
What is SEN in Barrow, Alaska (71º N) on June 21? December 21?

17. Group Exercise What is the Greenhouse Effect and why is it important?
What are the dominant greenhouse gases?

18. Terrestrial Radiation
Greenhouse Effect
Heating of Earth’s surface and lower atmosphere caused by strong absorption and emission of infrared radiation (IR) by certain atmospheric gases
known as greenhouse gases
Similarity in radiational properties between atmospheric gases and the glass or plastic glazing of a greenhouse is the origin of the term greenhouse effect
© AMS

19. Terrestrial Radiation
Greenhouse Effect
Responsible for considerable warming of Earth’s surface and lower atmosphere
Earth would be too cold without it to support most forms of plant and animal life
© AMS

20. How Greenhouse Effect Works
© AMS

21. Terrestrial Radiation
Greenhouse Gases
Water Vapor is the principal greenhouse gas
Clear-sky contribution of 60%
Other contributing gases:
carbon dioxide (26%)
ozone (8%)
methane plus nitrous oxide (6%)
© AMS

22. Terrestrial Radiation
Greenhouse Gases
Atmospheric window: range of wavelengths over which little or no radiation is absorbed
Visible atmospheric window extends
from about 0.3 to 0.7 micrometers
Infrared atmospheric window from
about 8 to 13 micrometers
© AMS