Sunshine Hours

Sunshine has traditionally been recorded using a Campbell Stokes Ball. Achieving the exactly same electronically is more difficult because we generally record solar energy rather than light.

Solar energy varies throughout the year depending on the height of the sun and the angle of incidence. There are technical ways of getting around this but they are extremely expensive and not commercially viable in this context. However the weather station software and hardware packages we sell offer some solutions.

Davis WeatherLink provides a report to calculate the total hours of bright sunshine during any given period. To do so you must enter a solar energy threshold above which is considered "bright sunshine". The default is 100 W/m2. WeatherLink calculates the amount of time the solar energy was above the threshold and reports that amount of time as the hours of bright sunshine. For this you will need a Davis Vantage Pro2 and either the Plus version or at least the addition of a solar sensor.

The same can be done in WeatherDisplay which offers more threshold options but is essentially the same thing. For this you ideally require a weather station that records solar energy (not UV) such as The Davis Vantage Pro2 Plus. The software does however include the possibility of using an additional temperature sensor with other makes of weather station. The sensor is housed in a glass jar exposed to full sun to create a proximity of a solar senor. However this later method will not have any kind of accuracy and might lead to premature failure of the sensor.