A tephigram is one of four

thermodynamic diagrams Thermodynamic diagrams are diagrams used to represent the thermodynamic states of a material (typically fluid) and the consequences of manipulating this material. For instance, a temperature–entropy diagram ( T–s diagram) may be used to demon ...

commonly used in

weather Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the ...

analysis and forecasting. The name evolved from the original name "T-

\phi

-gram" to describe the axes of

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

(T) and

entropy Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynam ...

(

\phi

) used to create the plot. Usually, temperature and

dew point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will cond ...

data from

radiosonde A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calcula ...

s are plotted on these diagrams to allow calculations of convective stability or

convective available potential energy In meteorology, convective available potential energy (commonly abbreviated as CAPE), is the integrated amount of work that the upward (positive) buoyancy force would perform on a given mass of air (called an air parcel) if it rose vertically thr ...

(CAPE). Wind barbs are often plotted at the side of a tephigram to indicate the winds at different heights.

Description

The tephigram was invented by

Napier Shaw Sir William Napier Shaw (4 March 1854 – 23 March 1945) was a British meteorologist. He introduced the tephigram, a diagram for evaluating convective instability in the atmosphere. He also served as president of the International Meteorological ...

in 1915 and is used primarily in the United Kingdom and Canada. Other countries use similar thermodynamic diagrams for the same purpose however the details of their construction vary. In the tephigram, isotherms are straight and have a 45 degree inclination to the right while isobars are horizontal and have a slight curve. Dry

adiabat In thermodynamics, an adiabatic process (Greek: ''adiábatos'', "impassable") is a type of thermodynamic process that occurs without transferring heat or mass between the thermodynamic system and its environment. Unlike an isothermal process, ...

s are also straight and have a 45 degree inclination to the left while moist adiabats are curved. The main reason that tephigrams are used by the British

Met Office The Meteorological Office, abbreviated as the Met Office, is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy and is led by CEO Penelope E ...

, the

Meteorological Service of Canada The Meteorological Service of Canada (MSC; french: Service météorologique du Canada – SMC) is a division of Environment and Climate Change Canada, which primarily provides public meteorological information and weather forecasts and warnings ...

, and

Met Éireann Met Éireann (; meaning " Met of Ireland") is the state meteorological service of Ireland, part of the Department of Housing, Local Government and Heritage. History The history of modern meteorology in Ireland dates back to 8 October 1860, wh ...

(Irish Meteorological Service) is the property that areas contained by the curves have equal energies for equal areas, leading to better comparisons of

CAPE A cape is a clothing accessory or a sleeveless outer garment which drapes the wearer's back, arms, and chest, and connects at the neck. History Capes were common in medieval Europe, especially when combined with a hood in the chaperon. Th ...

and hence convective systems.

References

Bibliography

* M.H.P. Ambaum, ''Thermal Physics of the Atmosphere'', published by Wiley-Blackwell, April 16, 2010, 240 pages. * R.R. Rogers and M.K. Yau, ''Short Course in Cloud Physics, Third Edition'', published by Butterworth-Heinemann, January 1, 1989, 304 pages. * J.V. Iribarne and W.L. Godson, ''Atmospheric Thermodynamics, 2nd Edition'', published by D. Reidel Publishing Company,

Dordrecht Dordrecht (), historically known in English as Dordt (still colloquially used in Dutch, ) or Dort, is a city and municipality in the Western Netherlands, located in the province of South Holland. It is the province's fifth-largest city after R ...

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

, 1981, 278 pages, ,

External links

Department of Meteorology, University of Reading
page about tephigrams including pdfs of blank printable colour and monochrome tephigrams. Atmospheric thermodynamics {{climate-stub

Description

See also

References

Bibliography

External links