The US Environmental Protection Agency Glossary on Climate & Weather

A-112

Note: Intended text and marked with: WIC, indicates that Question, Info, Comment, etc,

are from ‘whatisclimate’ (WIC)

The US EPA – Environmental Protection Agency - runs a ‘Glossary of Climate Change Terms’[1], offering as meaning for the term ‘climate’ only"average weather". The same texts are also used elsewhere[2]. Although it is not easy to discuss a term which is a layman’s imagination, and used to be in meteorology, “ a menial occupation that came on the pecking scale somewhat below the advertising profession”[3], some remarks have been made, which shall be improved whenever deemed possible.

EPA on Climate:
Climate in a narrow sense is usually defined as the "average weather" or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands of years. The classical period is 3 decades, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.[2]

QUESTIONS:

1. Can it make sense to define climate on the basis of weather, when weather has not been defined in the first place.
2. Who says which statistical data represent the ‘average weather’?
3. Is it every ones own guess which time period to use?
4. What is ‘classical’ in this respect? Has WMO defined ‘climate’, or have they been using the definition of their predecessor, the International Meteorological Organisation, as done in Warsaw 1935?
5. Who decides which variables are used? And: statistics on temperature, precipitation, and wind remain ‘historical data’ for the time and location of collection.
6. Can climate in a wider sense:
   1. be the state? NO;
   2. is the state, including a statistical description? NO, as climate is only statistics;
   3. is the state of the climate system? NO

EPA on Weather:

Atmospheric condition at any given time or place.

Comment: This statement is wrong. The atmosphere comprise a lot of conditions and ‘stuff’ including CO2 and the other Greenhouse Gases, which is not ‘weather’.

It is measured in terms of such things as wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation.

Comment: These parameters are those men usually observes and feels and meteorology is to provide the population with information in this respect. Weather explained in this way indicates clearly the common use by the general public.

In most places, weather can change from hour-to-hour, day-to-day, and season-to-season.

Comment: In all places and at every moment occur changes in temperature, humidity, atmospheric pressure, etc.

Climate in a narrow sense is usually defined as the "average weather", or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.

Comment: This section explains nothing about the ‘weather’.

A simple way of remembering the difference is that climate is what you expect (e.g. cold winters) and 'weather' is what you get (e.g. a blizzard).

Comment: A statistical description remains statistics regardless how named.

Footnotes

[1] http://www.epa.gov/climatechange/glossary.html#Climate

[2] For example: http://whatsyourimpact.co.nr/

[3] F. Kenneth Hare, 1979, “The Vaulting of Intellectual Barriers: The Madison Thrust in Climatology”; Bulletin American Meteorological Society; Vol. 60, No.10, October 1979, Pages 1171 – 1174.

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