Explanation of sunshine time terms

The number of hours that the sun actually shines on the ground in a place (the cumulative time that the ground observation station is directly radiated by the sun is equal to or greater than 120Win). Take the hour as the unit and take one decimal place.

The instruments for measuring sunshine hours include the concealed tube type (also called Tang Qiao type) heliometer and the focusing type (also called Compastock type) heliometer. The sunshine measured by e-meter is divided into sunshine hours and sunshine hours, and the ratio of actual sunshine hours to sunshine hours is called sunshine percentage or relative sunshine.

The actual sunshine hours in a place are always less than or equal to the sunshine hours due to the influence of weather conditions. If there are objects protruding from the ground around the measuring point, the actual sunshine hours after deducting the occlusion time of the objects are called topographic sunshine hours, which are always less than sunshine hours.