DAVIS Vantage Pro2 Plus User Manual page 52

Evapotranspiration (ET)
Evapotranspiration (ET) is a measurement of the amount of water vapor returned
to the air in a given area. It combines the amount of water vapor returned through
evaporation (from wet surfaces) with the amount of water vapor returned through
transpiration (exhaling of moisture through plant stomata) to arrive at a total.
Effectively, ET is the opposite of rainfall, and it is expressed in the same units of
measure (inches, millimeters).
The Vantage Pro2 uses air temperature, relative humidity, average wind speed, and
solar radiation data to estimate ET, which is calculated once an hour on the hour.
ET requires the optional solar radiation sensor.
Leaf Wetness
Leaf wetness (see "Optional Sensors & Transmitting Stations" on page 3) provides
an indication of whether the surface of foliage in the area is wet or dry by
indicating how wet the surface of the sensor is. The leaf wetness reading ranges
from 0 (dry) to 15. Leaf wetness requires an optional Leaf & Soil Moisture/
Temperature Station and is only available for Wireless Vantage Pro2 Stations.
Soil Moisture
Soil Moisture, as the name suggests, is a measure of the moisture content of the
soil. Soil moisture is measured on a scale of 0 to 200 centibars, and can help
choose times to water crops. The soil moisture sensor measures the vacuum
created in the soil by the lack of moisture. A high soil moisture reading indicates
dryer soil; a lower soil moisture reading means wetter soil. Soil Moisture requires
an optional Leaf & Soil Moisture/Temperature Station or Soil Moisture Station and
is only available for Wireless Vantage Pro2 Stations.
Time
The console has a built-in clock and calendar track the time and date. It
automatically adjusts for daylight saving time in most of North America and
Europe (and allows manual adjustment elsewhere) and for leap years, providing
you have entered the correct year, latitude and longitude, and daylight saving
settings in the Setup Mode.
48
T A-3: UV I
ABLE
Index Values
0 - 2
3 - 5
6 - 7
8 - 10
11+
NDEX
Exposure Category
Low
Moderate
High
Very High
Extreme