Do factors other than stratospheric ozone affect the amount of UV radiation that reaches the earth?
Yes. Although the ozone layer is the one constant defense against UV penetration, several other factors can have an effect: Latitude. Since the sun’s rays impact the Earth’s surface at the most direct angle over the equator they are the most intense at this latitude. Season. During winter months, the sun’s rays strike at a more oblique angle than they do in the summer. This means that all solar radiation travels a longer path through the atmosphere to reach the Earth, and is therefore less intense. Time of day. Daily changes in the angle of the sun influence the amount of UV radiation that passes through the atmosphere. When the sun is low in the sky, its rays must travel a greater distance through the atmosphere and may be scattered and absorbed by water vapour and other atmospheric components. The greatest amount of UV reaches the Earth around midday when the sun is at its highest point. Altitude. The air is thinner and cleaner on a mountaintop – more UV reaches there than at lower e
