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WMO - The authoritative voice & The term: Climat
Posted on 01.November 2009/AB

 The World Meteorology Organization is a specialized agency of the United Nations (UN). Within the UN system  the WMO understand itself as “the  authoritative voice on the state and behaviour of the Earth's atmosphere, its interaction with the oceans, the climate it produces and the resulting distribution of water resources”[1]. WMO originated from the International Meteorological Organization (IMO), which was founded in 1873. More than 180 States are members of WMO. 

 The WMO website does not spend much space on the term climate and weather. We failed to find a Glossary[2]. However the WMO site has a theme-section[3], which include the two terms in question. Concerning weather the section “Weather” offers no explanation but has the opening sentence: “Everyone is interested in the weather”, while subsection: What is Climate[4]  begins with the sentence: “At the simplest level the weather is what is happening to the atmosphere at any given time.”(A)  
In the same section the Organization offers for climate three options namely:

·         in a narrow sense Climate is usually defined as the "average weather,"(B)
        ·         in a more rigorously way, Climate is the statistical description in terms of the mean and variability of relevant quantities over a period of time (C), and 
       ·         in a broader sense, Climate is the status of the climate system which comprises the atmosphere, the hydrosphere, the cryosphere, the surface lithosphere and the biosphere (D).

None of the items is very clear and can hardly be regarded as explanatory. Here is a provisional brief comment on each item (A-D):

(A)     It is not very enlightening and not necessarily correct, for example

a.      The boundary between the Earth’s atmosphere (Kármán Line) and outer space is at an altitude of 100km, but weather happens only up to 17km (equator) and 7km (poles). 

b.      The reference to ‘any given time’ is questionable, as any time period longer than a few days, would  –according the next definition (B)- be: climate. 

(B)     Science can describe and work with ‘average weather’ only by means of statistics of physical observations. Once a statistic it remains a statistic. 

(C)     There is actually no difference between climate in a “narrow sense” (B) and in a more rigorously way (C), but a confirmation average weather shall mean a statistical description, whereby the reference to “the mean and variability of relevant quantities” is completely vague and unclear. 

(D)     It is hardly to see what is meant with “broader sense” and an example of a case explaining something in circularity. 

a.      A formula: Climate is the status of the climate system, makes no sense.

b.      According the given explanation of climate (B & C), climate system would mean

                                                               i.     Average weather system, or

                                                             ii.     A statistical description of relevant quantity system, 

which is in no way helpful.

c.      The word status indicates a situation, and not longer period of time. 

d.      The reference to the ‘climate system’ is at least confusing, as the elsewhere defined term emphasize the ‘interaction’ among the subject fields[5]. Has it be left unmentioned because status and interaction do not fit well together? 


WMO has had more than 130 years of time to formulate a clear and understandable language. The way they define, explain, and use the layman’s  terms weather and climate is hardly convincing. A scientific approach is invisible. Do they need another century to do better?


[1] WMO-Homepage/About us/WMO in brief; first paragraph  (visited: November 2009)

[2] Under Home/Theme/Topics there is a reference to a “Glossary (Meteoterm)” the link was not operable (IT-address not found) and a “Glossary (WMO Secretariat)”, which provides abbreviations only. See: 

[3] WMO op.cit (Fn.2); Go: Home/Themes/Weather or Climate; or: Home/Topics/Weather or Climate

[4] WMO-Home Page; Via Topic or Theme: Climate/Climate System/Understanding Climate/What is Climate

[5] UNFCCC, Article 2, para.3; . "Climate system" means the totality of the atmosphere, hydrosphere, biosphere and geosphere and their interactions.  

Fn.1 : Material/Figures: 

          The National Snow and Ice Data Center,