Using the Product
Connect the sensor following the steps in the Getting Started section of the user manual.
The sensor shows best performance when operated within recommended normal temperature and humidity range of 5–60°C and 20–80% RH, respectively. Long-term exposure to conditions outside normal range, especially at high humidity, may temporarily offset the relative humidity reading.
Go Direct Weather has the following measurement channels:
- Wind Speed
- Wind Direction
- Wind Chill
- Heat Index
- Dew Point
- Relative Humidity
- Absolute Humidity
- Station Pressure
- Barometric Pressure
This channel reports wind speed. The sensor uses an impeller-type anemometer with the axis of rotation parallel to the direction of the wind. The motion of a magnet in the impeller produces a signal proportional to wind speed. The reading is positive regardless of the direction of motion of the impeller.
Wind Direction (accessory required)
This channel reports the direction of the wind. The Go Direct Weather Vane accessory (order code WTHR-VANE) is required and mounting on a tripod is recommended. Once attached, your Go Direct Weather will rotate such that the wind will pass from the back of the sensor to the front. The direction from which the wind is coming will be reported in 10° increments, with 360° representing north and 90° representing east.
For the sensor to indicate true north at your location, the magnetic declination must be set. Magnetic declination is the angular difference between true north and the direction to which a magnetic compass points. This varies by location and changes over time. Your current magnetic declination can be determined by consulting any number of online calculators. It will consist of a numeric angular value and identified as either East or West. If your declination is identified as East, enter the value in the app as a positive number. If it is identified as West, enter it as a negative number.
For example, Vernier’s main office is near Portland, Oregon. At the time of this writing, its magnetic declination is 15° East. Therefore, the declination should be entered as 15. Portland, Maine, on the other hand has a declination of 15° West. Therefore, this would be entered as –15.
Follow these steps to set the magnetic declination for your location:
- Connect your Go Direct Weather.
- In Graphical Analysis 4 app, click or tap on the sensor icon in the bottom right corner of the application window. Click or tap the “i” next to the sensor ID to launch the device information dialog.
- On LabQuest, tap the Wind Direction meter, tap Go Direct, and select Device Details…
- Select Advanced at the bottom of the window.
- Enter the declination value for your location as a positive value for East and a negative value for West.
- Click or tap Save in Graphical Analysis 4 or Apply on LabQuest. The declination value is stored in the sensor and is applied each time the sensor is used.
This channel reports the wind chill. Wind chill is a calculation that measures how the wind and temperature impact the rate of heat loss from exposed skin. Wind chill is defined only for ambient temperatures below 50°F and wind speed greater than 3 mph. The reading is calculated based on an equation from the National Weather Service where WC is the wind chill, T is temperature in °F and W is wind speed in mph.
This channel measures ambient temperature.
This channel reports the heat index. The heat index measures the effect temperature and humidity have on how the human body perceives the temperature, also known as apparent temperature. The National Weather Service calculates the heat index value based on the Rothfusz regression. This analysis is dependent on the range of the temperature in °F and relative humidity in percent. Adjustments are made to the regression based on where these values lie. A simplified formula is used unless the heat index value is greater than 80°F; if it is higher, then the full regression equation is used.
This channel reports the dew point. The dew point is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The equation below is used to calculate the value where td is dew point temperature in °C, t actual temperature in °C, and RH actual relative humidity in %
This channel measures the relative humidity of the air. Relative humidity is a ratio of the actual amount of water vapor in the air to the potential fully saturated air. It is dependent on temperature and pressure.
This channel reports the absolute humidity. The absolute humidity is the mass of water vapor in a particular volume of dry air. The equation below is used to calculate the value where dv is absolute humidity in g/m3, t actual temperature in °C, and RH the actual relative humidity in %.
This channel reports the station pressure at the current location. Station pressure is the absolute pressure at any given point without any adjustment. It is the pressure exerted by the atmosphere due to gravity at that given location.
This channel reports barometric pressure. Barometric pressure is the station pressure adjusted to mean sea level. To accurately read barometric pressure, you must enter your elevation into the calibration for the channel.
Station and barometric pressure are equal at sea level. The equation below is used to calculate the value where po is pressure at sea-level in mbar, A is altitude, and p absolute pressure in mbar.
This channel reports altitude based on the pressure at your location in meters. The equation below is used to calculate the value where A is altitude, p absolute pressure in mbar, and po pressure at sea-level in mbar.
Care and Maintenance
Go Direct Weather contains a small lithium-ion battery. The system is designed to consume very little power and not put heavy demands on the battery. Although the battery is warranted for one year, the expected battery life should be several years. Replacement batteries are available from Vernier (order code: GDX-BAT-650).
Storage and Maintenance
To store Go Direct Weather for extended periods of time, put the device in sleep mode by holding the button down for at least three seconds. The red LED will stop flashing to show that the unit is in sleep mode. Over several months, the battery will discharge but will not be damaged. After such storage, charge the device for a few hours, and the unit will be ready to go.
Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If possible, store the device in an area that is not exposed to temperature extremes.
Important: Go Direct Weather is water resistant but not waterproof. It should never be immersed in water.
If water gets into the device, immediately power the unit down (press and hold the power button for more than three seconds). Disconnect the sensor and charging cable, and remove the battery. Allow the device to dry thoroughly before attempting to use the device again. Do not attempt to dry using an external heat source.