39
10. Appendix
Dewpoint
- Temperature point that is independent of the interaction between a
specific air pressure level, a specific temperature and a certain level of humidity. The
humidity in the air starts to condense at this point, the so-called dew; the humidity
condenses and precipitates as liquid (mist, vapor). If the dewpoint for water vapor
is below 32 °F (0 ˚C), then there is condensation in the form of snow or hoar frost.
Weather forecast
- Forecast about weather symbols calculated from the increasing
or decreasing speed of air pressure (trend).
These changes in the air pressure speed is the most decisive dimension for the
forthcoming weather; the absolute value has a lesser role to play. One can gener-
ally say that the increasing air pressure would mean better weather and falling air
pressure would then be a sign of bad weather.
Windchill-Equivalent-Temperature
- A fictional temperature that is felt by human
beings under certain conditions instead of the measured temperature and which
can be taken into account during low temperatures (for e.g. under 44 °F) to find
out how one would feel at certain temperatures, wind velocities and correspond-
ing clothing. These conditions are a temperature below 91.4 °F (33 ˚C) and a wind
velocity above 5.8 mph (2.6 m/s). Windchill is defined as the cooling effect of the
naked skin at assumed constant 91.4 °F (33 ˚C) skin surface temperature.
The higher the wind velocity and the lower the actual temperature, the stronger is
then the windchill effect.
The "felt" temperature is an approximation that can be compared to the so-called
feeling about the temperature and is taken into account along with the effect of
the emission effects of the sun, light reflection of the clouds, the light wave length,
etc.
Wind strength table (Beaufort)
Beaufort
Wind velocity km/h
Wind velocity mph
Description
0
0 - 0.7 km/h
0 - 0.4 mph
calm
1
0.7 - 5.4 km/h
0.5 - 3.6 mph
light air
2
5.5 - 11.9 km/h
3.7 - 7.4 mph
light breeze
3
12.0 - 19.4 km/h
7.5 - 12.1 mph
gentle breeze
4
19.5 - 28.5 km/h
12.2 - 17.7 mph
moderate breeze
5
28.6 - 38.7 km/h
17.8 - 24.0 mph
resh breeze
6
38.8 - 49.8 km/h
24.1 - 30.9 mph
strong breeze
7
49.9 - 61.7 km/h
31.0 - 38.3 mph
near gale
8
61.8 - 74.6 km/h
38.4 - 46.4 mph
gale
9
74.7 - 88.9 km/h
46.5 - 55.2 mph
strong gale
10
89.0 - 102.4 km/h
55.3 - 63.6 mph
storm
11
102.5 - 117.4 km/h
63.7 - 72.9 mph
violent storm
12
> 117.4 km/h
> 72.9 mph
hurricane
