What is Sunshine?
• The ultimate source of practically all of the energy for physical and biological processes occurring on the earth is radiation received from the sun. • Sunlight controls the length of our day. • It also determines what objects we can see, the colors they display and how far away we can see them (visibility). • The day length and number of sunshine hours are recorded in a weather observatory. How duration of sunshine is recorded? • Day length refers to the number of hours between sun rise and sun set. • Sunshine duration and intensity is a measure of the percentage of bright sunshine observed. It is related to the duration and intensity of direct solar radiation. • Sunshine duration also gives an indication of the presence of cloud. • The duration of sunshine is measured by a Campbell-Stokes sunshine recorder. • The recorder consist of a sphere arranged to focus the sun’s image on to a bent strip of card on which the hours are marked. • When the sun shines with sufficient intensity, t
