The Global Water Solar Shield is a ventilated sun shield, with high reflectiveness, low heat retention, and low thermoconductivity.  The unit is designed to protect the Global Water Humidity and Temperature sensors from direct sunlight that may affect the sensor's 4-20 mA output.

What is Relative Humidity?
Air moisture content is typically described by a relative humidity measurement.  Relative humidity is the ratio of the water vapor content to the concentration of water vapor that the atmosphere could hold.  In general, the relative humidity will vary inversely with air temperature so that the relative humidity is highest when the temperature is lowest, and vice versa.  Typically after sunrise, when the air warms, the relative humidity falls.  Relative humidity is typically given in a percentage reading.  The vapor in the air is considered at 100% relative humidity when the concentration of water vapor in air is equal to the water vapor concentration at saturation.

Why Measure Relative Humidity?
Relative humidity has a major effect on the environment.  Humidity readings provide a chance to control these effects.  Effects include causing discomfort in people or animals, damaging materials in warehouses or other storage facilities, affecting the climates for optimal production processes, impacting the quality of construction materials and many others.

What is Temperture and How is it Affected?
Temperature is typically measured in degrees Celsius of Frhrenheit.  To accuratly measure temperature the temperature sensor should be shielded from direct sunlight or precipitation and it should be adequately ventilated.  Usually "surface" air temperature is measured approximately two meters above the surface.

The factors that affect temperature sensors include latitude, the movement of air masses, solar radiation, and nearby bodies of water or land.  Typically solar radiation and latitude are the biggest influences on the temperature reading.

Humidity and Temperature Sensors Specifications

Humidity Sensor
Type: Capacitance
Output: 4-20 mA
Range: 0 to 100% RH
Accuracy: ±2% RH
Operating Voltage: 10-36 VDC
Current Draw: 3mA plus sensor output
Warm Up Time: 3 seconds minimum
Operating Temp: -40° to +55°C
Sensor Size: 1 1/2" diameter x 7"
Weight: 1/2 lb.

Temperature Sensor
Type: Precision RTD
Output: 4-20 mA
Range: -50°C to +50°C
Accuracy: ±0.2°F or ±0.1°C
Operating Voltage: 10-36 VDC
Current Draw: Same as sensor output
Warm Up Time: 5 seconds minimum
Operating Temp: -50° to +100°C
Sensor Size: 3/4" diameter x 4 1/2"
Weight: 1/2 lb.