Snowdon Weather Stations Project Technical Information

ABOUT THE WEATHER
Great interest has been shown in the installation of an automatic weather station on Snowdon summit at 1085 metres in North Wales. Until recently, there had been no high elevation automatic weather stations in Snowdonia. Yet the need for this information for mountain safety, weather forecasting, public information, research and teaching is considerable.

MOUNTAIN RESEARCH
The mountains of Snowdonia form a protected environment. Little, however, was known about some elements of the weather on the mountains; almost nothing was known, for example, about winter conditions in the mountains. The monitoring and understanding of mountain environments is a high profile activity in response to their global, regional and local importance identified at Rio in Agenda 21. The general public and the environmental and research communities now see mountains as essential and fragile areas providing water, diverse ecological habitats, refuges for rare flora and fauna, and important

for their amenity and recreation values. A notable feature of mountain areas, and one which was used to stress their importance in Agenda 21, is the steep climatic, environmental and ecological gradient, and hence diversity of habitats. A range of weather and climate stations are needed in order to understand these gradients more fully, and to be able to demonstrate just how environment is influenced by position and altitude. Two particular topics form a focus for research across the globe at present:

Our profile of weather stations providing live weather and images on the WWW is a first in the UK. The archive of climate data is now being used in research with UK and European collaborators.

All the weather elements measured are scanned every 5 seconds and the readings are stored in the memory of a 'DataLogger' at the individual site. The information stored in the datalogger is then be summarised over time.

Air temperature:
This is measured using a Stevenson screen to measure the ambient temperature. Two whip sensors, about a metre long, flex in the wind to stop any ice build up. These figures show the minimum, average and maximum temperatures measured for each period (degrees celsius).

Rain:
A tipping bucket rain gauge measures the total volume of rain falling during that period (millimetres). A straight-sided bucket would fill up to this level (mm) with that amount of rain.

Relative Humidity:
This is the ratio between the amount of water air holds and the amount it could possibly hold, this is given as a percentage. It is worth bearing in mind that as the Snowdon summit station is often in the clouds, it will show a high relative humidity (RH).

Sunshine:
A sensor at each weather station measures the total power of the sunshine in kilo Watts per square metre. Strong summer sunshine reaches about 900 w/m2.

Airflow:
Wind speed is measured using an anemometer in miles per hour (M.P.H.). The anemometer on the summit of Snowdon is 20m below the summit and will not always give a perfect reading. It is quite common to see exceptionally high wind speeds at Clogwyn Station which is on a very exposed ridge on Snowdon. When temperatures fall below zero in winter, rime ice may stop the anemometer from turning. Wind direction is measured in degrees, so 270° would convert to due west and 0° would convert to due north.

The weather station dataloggers sample the current weather conditions using over 20 different sensors, every 5 seconds. This data is stored in the datalogger to allow interrogation.

Every 15 minutes the radio receiver requests the latest data array from the datalogger which is transmitted over 10 km using radio signals. This is then put into a central database to allow easy archival and interrogation.

When someone looks at a web page, the web server requests the latest data 'array' from the database and puts the information into a web page for the public to read.

More information on how Campbell Scientific weather stations work:
www.campbellsci.co.uk