DAVIS and Vantage Pro, User Manual & Setup Manual

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Weather Conditions Measured/Calculated
Vantage Pro Manual Page 51
Solar Radiation
What we call “current solar radiation” is technically known as Global Solar
Radiation, a measure of the intensity of the sun’s radiation reaching a horizon-
tal surface. This irradiance includes both the direct component from the sun
and the reflected component from the rest of the sky. The solar radiation read-
ing gives a measure of the amount of solar radiation hitting the solar radiation
sensor at any given time, expressed in Watts /sq. m (W/m
2
).
Note: The Vantage Pro measures energy received in the spectral band between 400 and 1100 nm.
UV (Ultra Violet) Radiation
Energy from the sun reaches the earth as visible, infrared, and ultraviolet (UV)
rays. Exposure to UV rays can cause numerous health problems, such as sun-
burn, skin cancer, skin aging, and cataracts, and can suppress the immune sys-
tem. The Vantage Pro can help analyze the changing levels of UV radiation and
can advise of situations where exposure is particularly unacceptable.
!! CAUTION: Be aware, however, that the Vantage Pro’s UV readings do not take into account UV reflected
off snow, sand, or water, which can significantly increase the amount of UV to which you are exposed.
Nor does the Vantage Pro take into account the dangers of prolonged exposure to UV radiation. The
readings do not suggest that any amount of exposure is safe or healthful.
Do not use the Vantage
Pro to determine the amount of UV radiation to which you expose yourself . Scientific
evidence suggests that UV exposure should be avoided and that even low UV doses
can be harmful.
The Vantage Pro displays UV readings in two scales: MEDs and UV Index.
MED stands for Minimum Erythemal Dose, defined as the amount of sunlight
exposure necessary to induce a barely perceptible redness of the skin within 24
hours after sun exposure. In other words, exposure to 1 MED will result in a
reddening of the skin. Because different skin types burn at different rates, 1
MED for persons with very dark skin is different from 1 MED for persons with
very light skin.
Both the U.S. Environmental Protection Agency (EPA) and Environment Can-
ada have developed skin type categories correlating characteristics of skin with
rates of sunburn. Tables 3a and 3b below list these skin types.
T
ABLE
A2: EPA S
KIN
P
HOTOTYPES
S
KIN
P
HOTOTYPE
S
KIN COLOR
T
ANNING
& S
UNBURN HISTORY
1 - Never tans,
always burns Pale or milky white; alabaster Develops red sunburn; painful swelling, skin peels
2 - Sometimes tans,
usually burns Very light brown; sometimes
freckles Usually burns, pinkish or red coloring appears;
can gradually develop light brown tan