The Finnish Meteorological Institute's UV index service has been expanded. Three-day UV index forecasts covering the whole world are now available on the Institute's website. Forecasts for individual localities are presented as curves that graphically show the time of the day when the UV radiation is at its most intense. For Finland, the service also includes observation data from UV index measurements.
The UV index is a single figure showing the strength of ultraviolet radiation from the Sun at any given time. Protection against UV radiation is recommended when the index reaches the value of 3. The Finnish Meteorological Institute cautions against strong radiation when the index in Finland rises to 6.
As recommended by the UN, the UV index is used in the same way the world over. The highest values measured in Finland are 5-6, which can be reached on the southern coast in the height of the summer at noon. In the Mediterranean countries the UV index in summer is 8-10. Around the equator, the UV index can rise to about 15, and high in the mountains it can even exceed 20.
The main reasons for variations in the UV index are the measurement point on the globe, the season, and the time of the day. Other factors affecting the index are cloudiness, the altitude from the sea level, and the amount of ozone in the upper atmosphere. The Finnish Meteorological Institute's UV index forecast has been made for cloudless weather. The forecast takes note of the location and the ozone level.
The UV index forecasts can be checked out at www.fmi.fi/weather/warning_4.html.
The service is also available in Finnish (www.fmi.fi/UVI) and Swedish (sv.ilmatieteenlaitos.fi/vader/varningar_6.html).