Sunlight

Sunlight is the light and energy that comes from the Sun. When this energy reaches the earth's surface, it is called insolation. What we experience as sunlight is really solar radiation. It is the radiation and heat from the Sun in the form of electromagnetic waves.

The atmosphere affects the amount of solar radiation received. When solar radiation travels through the atmosphere, some of it is absorbed by the atmosphere (16%). Some of it is scattered to space (6%). Some of it is reflected by clouds (28%). About 47% of it reaches the Earth's surface.

Without sunlight, there could not be life on the Earth. Plants need sunlight for the process of photosynthesis. During photosynthesis the plants use the energy of the sunlight, water, and carbon dioxide, to create glucose (sugar). The glucose can later be used by the plant for energy or animals eat the plant and the glucose in it. Plants need sunlight to grow green. Without enough sunlight but with enough water, the plant grows very tall very quickly, but looks yellow and dehydrated, although when touched, the leaves are very moist.

Solar radiation can be both good and bad for a person's health. When in the light, the human body uses the ultraviolet part of sunlight to make its own Vitamin D. Without sunscreen too much ultraviolet light can cause sunburn and skin cancer. Sun angle makes difference in seasons on Earth as well as in the length of day and night.^[1] A high angle makes the tropics hot, and a low angle makes the arctic cold.

1. ↑ World Sunlight Map from die.net