Civil Engineering Reference
In-Depth Information
FIGURE 4-14
Rayleigh distributions of hours and energy per year with k = 2 and c = 10, 15, and 20 mph.
Figure 4-14
compares the speed and
the energy distributions with k = 2
(Rayleigh) and c = 10, 15, and 20 mph. As seen here, the relative spread
between the speed mode and the energy mode remains about the same,
although both shift to the right as c increases.
4.6.6
Digital Data Loggers
The mean wind speed over a period of time is obtained by adding numerous
readings taken over the period and dividing the sum by the number of
readings. Many digital data loggers installed over the last few decades col-
lected average wind speed data primarily for the meteorological purpose,
as opposed to assessing the wind power. They logged
the speed every hour,
and then averaged over the day, which in turn, was averaged over the month
and over the year. The averaging was done as follows:
