La Crosse Technology WS-2510 - Manual (Page 28)

28
meteorological office or by calculation: absolute air pressure ±0.11hPa per meter of the measuring location above/below
mean sea level).
Wind chill equivalent temperature
(perceived temperature)- A fictitious temperature, which the human body feels under
certain conditions instead of the measured temperature, and which can be used at low temperatures (e.g. less than 45°F
or 7°C) to say how comfortable one feels at certain temperatures and wind speeds whilst wearing appropriate clothing.
These conditions are a temperature below 92°F (33ºC) and a wind speed higher than 5.8 mph (2.6 m/s). Wind chill is
defined as the cooling effect of uncovered skin at an assumed constant 92°F (33ºC) skin surface temperature.
The higher the wind speed is and the lower the actual temperature, the more noticeable is the wind chill effect.
The “perceived temperature” is roughly comparable to the so-called felt temperature, which additionally takes into account
the radiation effect of the sun, light refection from the clouds, the light wavelength, etc.
Wind strength table (Beaufort)
Beaufort
Wind speed Description
0 0-0.4 mph (0 -0.7 km/h) calm
1 0.5-3.3 mph (0.7 -5.4 km/h) slight breeze
2 3.4-7.3 mph (5.5 -11.9 km/h) light breeze
3 7.4-12.0 mph (12.0 -19.4 km/h) weak breeze
4 12.1-17.6 mph (19.5 -28.5 km/h) moderate breeze
5 17.7-24.0 mph (28.6 -38.7 km/h) fresh breeze
6 24.1-30.9 mph (38.8 -49.8 km/h) strong wind
7 31.0-38.3 mph (49.9 -61.7 km/h) stiff wind
8 38.4-46.3 mph (61.8 -74.6 km/h) stormy wind
9 46.4-55.2 mph (74.7 -88.9 km/h) storm
10 55.2-63.6 mph (89.0 -102.4 km/h) heavy storm
11 63.7-72.9 mph (102.5 -117.4 km/h) near hurricane storm
12 > 73 mph (117.4 km/h) hurricane
Units
ºF
=[ ºC ] * 9 /5 +32
ºC =([º F ]– 32 )*5 /9
mmHg =[hPa ] *0.75006
inHg =[hPa ] *0.02953
m/s
=[km/h ] //3.6 =[km/h ] *0.27778
knots =[km/h ] //1.852 =[km/h ] *0,53996
mph =[km/h ] //1.609 =[km/h ] *0.6215
in
=[mm ] //25.4 =[mm ] *0.03937
ft =[m ] //0.3048 =[m ] *3.28084
cu.in. =[ml ] //16.387 =[ml ] *0.061024.94
The Comfort Indicator (☺ ) represents the climatic conditions, for which the following table is used (the symbol
status shows the area of validity):
Temperature Humidity
20% 30% 35% 40% 45% 50% 55% 60% 65% 70%
< 64.4°F (18ºC)
64.4-67.8°F (18-19.9ºC)
67.9-71.4°F (20-21.9ºC) ☺ ☺ ☺ ☺
71.5-75.1°F (22-23.9ºC) ☺ ☺ ☺ ☺
75.2-78.6°F (24-25.9ºC) ☺ ☺ ☺ ☺
78.7-82.3°F (26-27.9ºC)
over 82.4°F(28ºC)
It can be seen from this that, depending on the ratio of temperature to humidity, there are clearly bounded areas, which
are defined as a comfortable or an uncomfortable climate. Hence, one finds a humidity level of 30% at a temperature of
77°F (25ºC), for example, to be too dry (e.g. heating air) and one above 60% to be oppressive.