DAVIS Vantage Pro2 User Manual download pdf (Page 26)

General

returned through evaporation (from wet vegetation surfaces and the stoma of

leaves) with the amount of water vapor returned through transpiration (exhal-

ing of moisture through plant skin) 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 Weather Envoy uses air temperature, relative humidity, average wind

speed, and solar radiation data to estimate ET. (ET is calculated once an hour

on the hour.)

Please note that calculating ET requires the optional solar radiation sensor.

Leaf Wetness

Note: Leaf Wetness is only available with the wireless Weather Envoy using the optional

Leaf and Soil Moisture/Temperature station (#6345) with a Leaf Wetness sensor

(#6420).

Leaf wetness provides an indication of whether the surface of foliage in the

area of the sensor is wet or dry by indicating how wet the surface of the sensor

is. The leaf wetness reading ranges from 0 (dry) to 15.

Soil Moisture

Note: Soil Moisture is only available with the wireless Weather Envoy using the optional

Leaf and Soil Moisture/Temperature station (#6345) with a Soil Moisture sensor

(#6440).

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 vac-

uum 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.

Time

The Weather Envoy has a clock and a calendar for tracking time and date. The

calendar automatically adjusts during leap years and daylight savings, provid-

ing you have entered the correct year, latitude and longitude, and daylight sav-

ings settings in the Setup Mode.

Specifications

General

Operating Temperature. . . . . . . . . . . .+14° to +140°F (-10° to +60°C)

Non-operating Temperature . . . . . . . .-13° to +158°F (-25° to +70°C)

Current Draw, Wireless . . . . . . . . . . .0.90 mA average, 20 mA peak, (plus 0.125

mA for each optional wireless transmitter in

use) at 4 to 6 VDC

Current Draw, Cabled . . . . . . . . . . . .10 mA average, 15 mA peak at 4 to 6 VDC

AC Power Adapter . . . . . . . . . . . . . . .5 VDC, 200 mA, regulated

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DAVIS Vantage Pro2 User Manual Page 26