1. Temperature Data in Climate Studies

2. Thermometers Different substances react to temperature changes differently. Liquid-in glass thermometer

3. Bimetal Strip Two metals expand and contract unequally when heated or cooled. Causes the strips to curl. The change corresponds to the change in temperature

4. Thermograph A recording thermometer Changes in the curvature of the bimetal strip move a pen arm. Pen marks temperatures on a calibrated chart that is attached to a clock-driven, rotating drum

5. Thermogram

6. Electrical Thermometers Thermisters (thermal resister): (1)Resistance to current is temperature dependent. (2)Higher temp = higher resistance, resulting in a reduction in flow of current (3)Measures flow of electricity which is calibrated in degrees of temperature. (4) Commonly used in thermostats and radiosondes.

7. Location of Thermometers  Inaccurate readings could result from placement (e.g. near a heat radiating surface or in the Sun)  Ideal placement is in an instrument shelter. Standard NWS shelter constructed of white pine, louvered on all sides. Provides protection from Sun, wind, and precipitation.

8. Balloons and Radiosondes Radiosondes are lightweight instrument packages that transmit data. They are released twice daily. Lower AltitudesHigh Altitudes

9. Temperature Data Used in Climate Study Average Daily Temperature: Average of the highest and lowest temperature for a day. Daily Temperature Range: Difference between the highest and lowest temperatures for a day. Monthly AverageTemperature: Average of each of the daily average temperatures for a month. Annual AverageTemperature: Average of the each of the average monthly temperatures for a year. Annual Temperature Range: Difference between the highest and lowest average monthly temps for a year.

10. For Surface Conditions  Weather information at a particular point is transmitted and plotted on a surface map at that station’s location.  The arrangement of the data around the station location is called a station model and is standardized by international agreement.  Units are not plotted  Air Pressure uses an encoded format

11. For Upper Air Data Temperature data is plotted in Celsius Air Temp ( o C) Air Temp. – Dew Point Temp. (T-T d ) -10 15 Referred to as the “temperature dewpoint spread” The dewpoint temperature is never higher than the air temperature.  The dewpoint temperature is -25 o C

12. Another Upper Air Station Model Example Air temperature: -2 o C Dewpoint Temperature: -10 o C -2 8 What is the temperature dewpoint spread?

13. Isotherms A type of isloline (Also called an isopleth) connecting points of equal temperature. The larger the range in temperatures, the larger the interval used on the map. Example using a 10 o F interval 40 63 50 61 38 44 40 46 34 57 66 50 40 49 68 40 50 60 Infer the 60 o F isotherm’s location, even though no 60 o F value is plotted on the map.

14. United States Isotherm Map

15. Average Temperature January

16. Average Temperature July

17. Global Annual Temperature Ranges

18. Climographs