Robert W. Christopherson Charlie Thomsen Chapter 5 Global Temperatures

Frozen tundra, very sensitive to global temperature change. Temperature increase in the polar region is more than double the rate of the rest of the globe.

The Sad Face of Melting Picture taken by Michael Nolan, a oceanic photographer, on July 16, 2009 in Norway

Temperature Concepts and Measurement Principal Temperature Controls Earth’s Temperature Patterns Air Temperature and the Human Body Global Temperatures

Temperature is a measure of average kinetic energy (motion) of individual molecules in matter. Heat always transfer in the direction from higher temperature to lower temperature. High temperature does not necessarily mean more heat. Temperature

Temperature Scales Fahrenheit Celsius Kelvin Measuring Temperature Mechanical (shrink/expansion) Electric Temperature Concepts and Measurement

Temperature Scales Figure 5.1

Thermometer and Instrument Shelter Figure 5.2Figure 5.3 Min-max thermometer

Electric Device: Thermal Couple and Thermistor Thermistor: is a type of resistor whose resistance varies with temperature. The word is a portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self- resetting over current protectors, and self- regulating heating elements. Thermal Couple: In 1822, an Estonian physician named Thomas Seebeck discovered (accidentally) that the junction between two metals generates a voltage which is a function of temperature. Unlike a thermometer, the electrical signals from a thermal couple or thermistor can be logged automatically with much higher accuracy.

What do we Care About Temperature 1.It is one of the most important weather and climate factors 2.All living species, plants, animals or microbes, have a suitable temperature range to live. 3.All biological and many physical processes are influenced by temperature i)Plant growth ii)Decomposition of plant residuals iii)Melting of ice and snow iv)Evaporation of water 4.Commonly used temperature i) Effective temperature: usually refers the temperature above the minimum required for a particular plant to be active (e.g. corn or peas ). For most plant, it is 5 o C. ii) Growing Degree Days: sum of mean daily temperature above the effective temperature. A very good predictor for phenology, e.g. time to flowering, time to harvest etc. iii) Extreme low/high temperature: can be a determinant factor limiting certain species spatial distribution.

Mean Temperatures 1.During the old days when there is no automatic data logging, staff at meteorological stations took a reading on their instrument four times a day: 02:00, 08:00, 14:00, and 20:00. The mean daily temperature is the mean of the four measurements. 2.Average of daily maximum and minimum temperature. 3.Modern automatic technology can set the instrument to measure the temperature every second and provide us with a mean at any time interval we want 4.Monthly Mean Temperature: adding daily mean temp and then divide the sum by the number of days in a month. 5.Annual Mean Temperature: adding the monthly mean temperature, and divide the sum by 12.

Latitude Affects insolation, which is the primary factor causing the spatial variation of temperature on Earth surface. Altitude High altitude has greater daily range High altitude has lower annual average Cloud Cover: Globally, 50% at any time. High albedo Moderate temperatures – cooler days, warmer nights Sun Declination angle (Season) Land and Water Principal Temperature Controls

Latitude and Temperature Figure 5.4

Altitude Figure 5.5

Evaporation Transparency Specific heat Movement Ocean currents and sea-surface temperatures Marine vs. continental effects Land–Water Heating Differences

Figure 5.7

Land Is Opaque Figure 5.8

The Gulf Stream Figure 5.10 Red/orange: o C Yellow/green: o C Blues: o C Purple: 1-9 o C

Marine and Continental Climates: Vancouver vs. Winnipeg Figure 5.12

Figure 5.13 Marine and Continental Climates: San Francisco vs. Wichita, KS

Marine and Continental Climates: Trondheim vs. Verkhoyansk Figure 5.16

January Temperature Map Thermal equator movement southward More pronounced over large continents July Temperature Map Thermal equator movement northward More pronounced over large continents Annual Temperature Range Map Continentality Earth’s Temperature Patterns

(b) (c) (a) January Temperatures Figure 5.14 Isotherm (iso=equal, therm=temperature: a line collects the points on the map that have the same temperature. The closer the line is, the greater the temperature gradient, i.e. the faster the temperature changes in space.

January Temperatures Figure 5.14 Note the coldest and hottest areas are both on land.

(c) (b) (a) July Temperatures Figure 5.17 Thermal equator migrated north.

July Temperatures Figure 5.17 There is a greater seasonal N-S shift for the thermal equator on land than in oceans! Why?

Global Temperature Ranges Figure 5.19

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

Wind Chill Table Figure FS 5.1.1

Heat Index Table Figure FS 5.1.2