Actually knowing that 1 mm rainfall is 1 L/m² is quite useful, even though
it is more simply stated as the former. It tells you how many watering cans
worth of rain your garden gets during a shower (obviously divide by the
capacity of the can in litres).
Phil Hall
----- Original Message -----
From: "Hillger, Don" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[email protected]>
Sent: Wednesday, October 26, 2005 4:22 PM
Subject: [USMA:35008] Re: Rain measurement in Europe
Official World Meteorological Organization (WMO) guidance for rainfall
specifies it to be given in millimeters. So the use of volume per unit
area must be old practice that is hard to overcome.
Don
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf
Of Tom Wade
Sent: Wednesday, 2005 October 26 07:05
To: U.S. Metric Association
Subject: [USMA:35006] Re: Rain measurement in Europe
Harry Wyeth wrote:
> I recently returned from Spain, where I viewed a TV news program about
> flooding in part of that country. The reporter stated that the
> rainfall
> had been in the amount of 8.-something liters per square meter within a
> one hour period.
>
> Anyone have any idea why she made it so complicated? Why not just say
> rainfall in the amount of 8.xx cm, period? Is this a European thing?
I have heard that this practice is common in Europe, although in Ireland,
rainfall is quoted in mm (probably because it used to be quoted in
inches). However, mm of rainfall (not cm) and liters
per square meter actually comes to the same thing, 8.6 mm of rain is
actually 8.6 L/m².
See http://www.fao.org/docrep/R4082E/r4082e05.htm
As for the why, I agree with you. Although the formal units used are
more correct (how can you measure a liquid as a length?) and therefore
to be preferred in a scientific article, the use of mm is more intuitive
to the TV viewer, as he can visualize the amount of rain needed to
produce
flooding that deep.
---------------------------------------------------------
Tom Wade | EMail: tee dot wade at eurokom dot ie
EuroKom | Tel: +353 (1) 296-9696
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