Weather and Climate Chpt. 3

liquid-in-glass thermometer

a device for measuring temperature that consists of a tube with a liquid filled build at one end. the expansion or contraction of the fluid indicated temperature.

isotherm

a line connecting points of equal air temperature.

growing degree-days

a practical application of temperature data for determining the approximate date when crops will be ready for harvest.

celsius scale

a temperature scale (once called the centigrade scale) used where the metric system is in use. For water at sea level, 0 is designated the ice point and 100 the steam point.

Fahrenheit scale

a temperature scale used int eh english system. for water at sea level, 32 is designated the ice point and 212 the steam point.

Kelvin or absolute scale

a temperature scale used primarily for scientific purposed and having intervals equivalent to those on the celsius scale but beginning at absolute zero.

maximum thermometer

a termometer that measures the maximum temperature for a given period in time, usually 24 hours. a constriction in the base o the glass tube allows mercury to rise but prevent it from returning to the bulb until the thermometer is shaken or whirled.

minimum thermometer

a termometer that measures the minimum temperature for a given period of time, usually 24 hours. by checking the small dumbbell shaped index the min. temp. can be read.

bimetal strip

a thermometer consisting of two thin strips of metal welded together, which have widely different coefficients of thermal expansion. when temperature changes, the two metals expand or contract unequally and cause changes in the curvature of the element. commonly used in thermographs.

annual mean temperature

an average of the 12 monthly means

thermistor

an electric thermometer consisting of a conductor whose resistance to the flow of current is temperature dependent; commonly used in radiosondes

thermometers

an instrument for measuring temperature; in meteorology, generally used to measure the temperature of the air

thermograph

an instrument that continuously records temperature

cooling degree-day

each degree of temperature of the daily mean about 65 F is counted as one. the amount of energy required to maintain a certain temperature in a building is proportional to the total.

heating degree-days

each degrees of temperature of daily mean below 65F is one. the amount of heat required to maintain a certain temperature in a building is proportional to total.

fixed points

reference points, such as the steam point and the ice point, used in the construction of temperature scales.

specific heat

the amount of heat needed to raise 1 gram of a substance 1C at sea level atmospheric pressure

temperature gradient

the amount of temperature change per unit of distance.

daily temperature range

the difference between the maximum and minimum temperatures for a day.

annual temperature range

the difference between the warmest and coldest monthly means

daily mean temperature

the mean temperature for a day that is determined by averaging the hourly readings or by averaging the maximum and minimum temperatures for a day.

ice point

the temperature at which ice melts.

steam point

the temperature at which water boils.

monthly mean temperature

the temperature for a month that is calculated by averaging the daily means.

absolute zero

the zero point on the Kelvin temperature scale, representing the temperature at which all molecular motion is presumed to cease.

controls of temperature

those factors that cause variations in temperature from place to place, such as latitude and altitude.