1. Copyright © 2013 Pearson Education, Inc. The Atmosphere: An Introduction to Meteorology, 12 th By: Lutgens and Tarbuck Lectures by: Heather Gallacher, Cleveland State University Chapter 3: Temperature Copyright © 2013 Pearson Education, Inc.

2. For the Record: Air-Temperature Data  Basic calculations:  Daily mean  Average of 24 hourly readings  Daily temperature range  Difference of daily high and low  Monthly mean  Average of daily means  Annual mean  Average of monthly means  Annual temperature range  Difference of highest and lowest monthly mean

3. Copyright © 2013 Pearson Education, Inc. For the Record: Air-Temperature Data  Isotherms:  Line connecting equal temperature

4. Copyright © 2013 Pearson Education, Inc. Why Temperatures Vary: The Controls of Temperature  Controls of temperature:  Differential heating of land and water  Ocean currents  Altitude  Geographic positioning  Cloud cover and albedo

5. Copyright © 2013 Pearson Education, Inc. Land and Water  Water is mobile.  Temperatures rise and fall slower on water than on land.  Land is opaque.  Heat is absorbed only on the surface.  Specific heat is three times greater for water than land.  Evaporation is greater over water.

6. Copyright © 2013 Pearson Education, Inc. Ocean Currents

7. Copyright © 2013 Pearson Education, Inc. Altitude  Temperatures decrease with altitude.  The atmosphere is thinner at higher altitudes.  Higher altitudes produce a greater daily temperature range.

8. Copyright © 2013 Pearson Education, Inc. Geographic Position

9. Copyright © 2013 Pearson Education, Inc. Cloud Cover and Albedo  More clouds cause lower surface temperatures during the day, but warmer temperatures at night.  A high albedo reduces surface temperature.

10. Copyright © 2013 Pearson Education, Inc. World Distribution of Temperature

11. Copyright © 2013 Pearson Education, Inc. World Distribution of Temperature  There is a smaller temperature range at the equator.  There is a larger temperature range at higher latitudes.  Interiors of continents have a higher temperature range.  Coastal regions have a smaller temperature range.

12. Copyright © 2013 Pearson Education, Inc. Cycles of Air Temperatures  Daily temperature variations:  Vary by seasons.  Vary with cloud cover.

13. Copyright © 2013 Pearson Education, Inc. Cycles of Air Temperatures  Magnitude of daily temperature change:  At mid and low latitudes, a high sun angle results in a large variation throughout the day.  At higher latitudes, a low sun angle results in lower temperature variations.  Windward coasts have small variations.  Inland areas have larger variations.  Temperature change depends on the amount of cloud cover and water vapor.

14. Copyright © 2013 Pearson Education, Inc. Cycles of Air Temperatures  Annual temperature variations:  Highest and lowest mean temperatures do not coincide with maximum or minimum incoming solar radiation.  In the northern hemisphere, August has the highest mean temperature, while June has the highest incoming solar radiation.

15. Copyright © 2013 Pearson Education, Inc. Temperature Measurement  Mechanical thermometers:  Liquid in glass  Maximum thermometer—mercury  Minimum thermometer—alcohol  Thermograph—bimetal strip  Electrical thermometers:  Thermistor—electrically resistant at different temperatures  Very fast

16. Copyright © 2013 Pearson Education, Inc. Temperature Measurement  Instrument shelters:  White box  Louvered sides  Over grass  1.5 m above ground

17. Copyright © 2013 Pearson Education, Inc. Temperature Scales  Fixed points:  Ice point  Ice melts  32° F, 0° C, 273 K  Steam point  Water boils  212° F, 100° C, 373 K

18. Copyright © 2013 Pearson Education, Inc. Temperature Scales  Fahrenheit 1715  Celsius 1742  Kelvin  Absolute, no negatives

19. Copyright © 2013 Pearson Education, Inc. Temperature Scales

20. Copyright © 2013 Pearson Education, Inc. Heat Stress and Wind Chill: Indices of Human Discomfort  Apparent temperature is the temperature a person perceives.  Heat stress is caused by high temperature and high humidity.  Sweat does not evaporate from body.  Feels hotter  Heat stress index

21. Copyright © 2013 Pearson Education, Inc. Heat Stress and Wind Chill: Indices of Human Discomfort

22. Copyright © 2013 Pearson Education, Inc. Heat Stress and Wind Chill: Indices of Human Discomfort  Wind chill is the cooling power of moving air.  Evaporates moisture  Cools body  Feels colder  Wind chill chart

23. Copyright © 2013 Pearson Education, Inc. Heat Stress and Wind Chill: Indices of Human Discomfort

24. Copyright © 2013 Pearson Education, Inc. End Chapter 3