Temperature

A. Statistical Analysis 1.______________Temperature: Average of the highest and lowest temperature for a day. 2.Daily Temperature : Difference between the highest and lowest temperatures for a day. 3.Monthly Temperature: Average of each of the daily average temperatures for a month. 4.Annual Temperature: Average of the each of the average monthly temperatures for a year. 5.Annual Temperature : Difference between the highest and lowest average monthly temps for a year. Average Daily Range Average Range

B.Measuring Temperature 1.______________ (a)Different substances react to temperature changes differently. (b)Liquid-in glass thermometer Thermometers

c. Maximum and Minimum Thermometers Maximum Thermometer: –As temperature rises, mercury expands and is forced through the constriction which prevents a return of mercury into the bulb when temperature falls

Minimum Thermometer: – A small dumbbell-shaped index in a low density liquid (alcohol) is pulled toward the bulb as the temperature drops and the column shortens. –The index remains at the lowest temperature reached as liquid drains past it when temperature rises. It must be mounted horizontally

2._________strip: a.Two metals expand and contract unequally when heated or cooled. b.Causes the strips to curl. c.The change corresponds to the change in temperature Bimetal

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

Thermogram

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

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

C. Temperature Scales A quantitative measurement of temperature requires scales based in fixed points which are reference points A quantitative measurement of temperature requires scales based in fixed points which are reference points.

1. Fahrenheit Scale a.Devised by German physicist Daniel Fahrenheit in 1714 b.Fixed Points (1) point = lowest temperature of a mixture of ice, water, and common salt. (2) point = human body temperature (he used 96 o ). (3) ___________ is 32 degrees (melting point of ice) and 212 degrees (boiling point of water) called the point and point respectively. ice Range steam Zero Second

2. Celsius Scale a.Devised by Swedish astronomer Anders Celsius in 1742 b. Scale c.Fixed Points (1)Zero Point = 0 degrees (melting point for water) (2)Second Point 100 degrees (boiling point for water) (3)Also called centigrade but now referred to as Celsius in honor of its inventor. Decimal

3.Kelvin Scale a.Developed by Scottish mathematician and physicist Lord Kelvin in the mid 1800's. b.The scale. c.Used for some scientific endeavors d.Fixed Points (1)Uses 100 degrees between the melting point of ice and boiling point of water. (2)Ice point = 273 (3)Zero point represents the theoretical temperature, absolute zero. e.No negative values f.Degrees Kelvin are called Kelvins which are abbreviated as K, with no degree symbol used (ex. 273 K). absolute

If Temperature is provided in degrees Celsius, convert to degrees Fahrenheit Two degree increments One degree increments

Conversions: Celsius -Fahrenheit Relationship o F = (1.8 x o C) +32 o C = o F –

Celsius-Kelvin Conversions o C = K K = o C + 273

D.Map Representation of Temperature 1.________Models a.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 Station

The Station Model

b. Plotting Temperature on a Station Model 1.Temperature is plotted in the upper ____ of the circle. 2.Always plotted in degrees ___________ 3.Units ( o F) are __________. left Fahrenheit omitted

Practice Examples Plot a temperature of 40 o F. Plot a temperature of 12 o C

2. Isotherms a.____________ connecting points of equal temperature. b.The larger the range in temperatures, the larger the interval used on the map. Example using a 10 o F interval Isolines Infer the 60 o F isotherm’s location, even though no 60 o F value is Plotted on the map

United States Isotherm Map

E. Factors that Cause Temperatures to Vary from Place to Place

1. Land and Water a. Differential___________________: A mass of soil heats and cools _______than an equal mass of water. heating and cooling faster

b.Land is opaque and water is more _________________ (1)Heat is absorbed by land only at the ________________, within the top few centimeters. (2)Solar radiation penetrates to greater depths in water, to depths of several meters. transparent surface

C.Water is highly mobile. (1)_______________ currents can distribute heat throughout a ______________mass. (2)Heat remains near the __________of land. No mixing can occur Convection surface greater

d.Specific Heat (1)The specific heat of liquid water is more than three times____________ than for land. (1)Water requires__________ heat to raise its temperature the same amount as an equal quantity of land greater more

2.Geographic Location a.Coastal Locations vs. Inland Locations (1)Coastal regions have their yearly temperatures ___________by the nearby presence of a body of water. (2)Coastal regions will have ____________yearly temperature ranges than inland regions (a)___________ summer temperatures (b)___________winter temperatures moderated smaller Cooler Warmer

b.Windward Coast vs. Leeward Coast (1)Windward:Prevailing winds from the ocean will result in a _________annual temperature range (2)Leeward: __________ temperature range because winds do no carry the ocean’s influence on shore. smaller Larger Prevailing Winds

c.Latitude (1)On the average, as latitude increases average annual temperature _____________ (2)Higher latitudes also have a greater annual temperature __________. decreases range

Global Annual Temperature Ranges

Climographs

d. Northern Hemisphere vs. Southern Hemisphere (1)The Southern Hemisphere has a_____________ percentage of water than the Northern Hemisphere (81% covered - 20 percent more than the N. Hemisphere). (2)__________ temperature variations in the Southern Hemisphere. greater Smaller

3.Altitude a.As altitude increases, average annual temperature ____________. b.Increased altitude results in a _______daily temperature range because the greater intensity of insolation due to the less dense air. Quito, Ecuador is high in the Andes Mountains Guayaquil, Ecuador is near sea level. decreases larger

4. Ocean Currents a.Currents moving towards lower latitudes are ______. b.Currents moving away from the equator are ________. c.Caused by frictional drag on the surface by _______. d.Affect coastal areas cold warm wind

Ocean Currents

5.Cloud Cover a.During the day, clouds __________ insolation back to space. b.At night, minimum temperature will not fall as low. Clouds ________ terrestrial radiation and emit a portion of it toward the surface. c.Clouds _________the daily temperature range. reflect absorb reduce

F. Temperature Data Applications

1. __________Degree Days a.Evaluates energy demand and consumption b.Assumes that heating is not required in a building when the daily mean temperature is 65 o F (18.3 o C) or higher. Heating c. Each degree of temperature lower than 65 o F equals one heating degree day. d. Subtract the daily mean below 65 o F from 65 o F. e. Amount of heat required to maintain a desired temperature in a building is proportional to the number of heating degree days (a linear relationship). f. Heating “season” is July 1 through June 30 and heating degree days are cumulative 1000’s o F

2. ________Degree Days a.Evaluates amount power required to cool a building b.Uses 65 o F as the base temperature by subtracting this number from the daily mean temperature. Cooling 1000’s o F

3. ________ Degree Days a.Helps determine the approximate date when crops will be ready for harvest. b.Difference between the daily mean temperature and the base temperature of the crop (minimum temperature required for it to grow). c.It accumulates with the onset of the growing season Growing

4. Wind Chill 1.Wind cools the body (increase evaporation, a cooling process, from the skin). 2.Estimate of human discomfort.

New Chart effective November 2001 Accounts for wind effects at face level More accurately portrays body heat-loss estimates Tested on human subjects Includes a frostbite indicator