Meteorology and Climatology Ch 3

liquid-in-glass thermometer

A device for measuring temperature that consists of a tube with a liquid-filled bulb at one end. The expansion or contraction of the fluid indicates temperature.

isotherm

A line connecting points of equal air temperature

Kelvin scale

A temperature scale (also called absolute scale) used primarily for scientific purposes and having intervals equivalent to those on the Celsius scale but beginning at absolute zero K=*C+273

Celsius scale

A temperature scale (at one time called the centigrade scale) devised by Anders Celsius in 1742 and used where the metric system is in use. For water at sea level, 0* is designated the ice point and 100* the steam point *C= (*F - 32)/1.8 *C=K - 273

Fahrenheit scale

A temperature scale devised by Gabriel Daniel Fahrenheit in 1714 and used in the English system. For water at sea level, 32* is designated the ice point and 212* the steam point *F= (1.8 x *C) + 32

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.

maximum thermometer

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

minimum thermometer

A thermometer that measures the minimum temperature for a given period of time, usually 24 hours. By checking the small dumbbell-shaped index, the minimum temperature can be read

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.

thermometer

An instrument for measuring temperature; in meteorology, a thermometer is generally used to measure the temperature of the air

thermograph

An instrument that continuously records temperature

fixed points

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

apparent temperature

The air temperature perceived by a person

specific heat

The amount of heat needed to raise 1 gram of a substance 1*C 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 of the 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, more commonly, by averaging the maximum and minimum temperatures for a day.

monthly mean temperature

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

ice point

The temperature at which ice melts

steam point

The temperature at which water boils

absolute zero

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