The Sun is the primary source of ultraviolet light within the Earth's atmosphere. Ultraviolet light appears in different wavelengths and energy levels. Its effects on living organisms can vary depending on the type of organism and whether any other factors or stressors are at work. As a result, ultraviolet light can have both damaging and beneficial effects on living organisms.
Ultraviolet light consists of electromagnetic radiation waves that appear within different wavelength ranges. The shorter the wavelength the stronger the energy contained inside the wave. According to the NASA Earth Observatory ultraviolet light comes in longer wave forms, or UV-A rays and shorter wave forms, or UV-B rays. Living cells can undergo damaging effects when exposed to UV-B light rays. The energy wavelengths contained inside UV-B light rays can penetrate cell membranes and alter the DNA materials within a cell's nucleus. Since DNA materials direct any building processes that take place within the cell, alterations can result in cell mutations, or cells that die off. Fortunately, living cells have developed a means for repairing DNA damage by removing altered portions of the molecule and replacing them with the needed materials.
Effects on the Human Body
The effects of ultraviolet radiation on the human body can vary depending on the amount of exposure. According to the NASA Earth Observatory, UV-A rays have beneficial effects on human skin by triggering essential Vitamin D secretions for the body. On the other hand, excessive exposure to UV-A rays results in sunburn and also cause cataracts to form in the eyes. The DNA damage caused by exposure to UV-B rays can eventually develop into skin cancer as well as alter or suppress normal immune system function. When the immune system is affected, conditions such as Herpes simplex virus and skin lesions can start to appear along the skin's surface. UV-B exposure to the eyes can also result in cataracts as well as vision impairment.
The effects of ultraviolet light on the environment appear within marine organisms, plant life and in the biogeochemical cycles that support and balance the Earth's ecosystems, according to the NASA Earth Observatory. Marine organisms such as sea urchins exist within shallow water environments, which make them susceptible to UV-A effects in the form of cell mutations and impaired reproductive functions. Plant life forms also experience the effects of UV-B rays on cell processes and DNA materials. These effects appear within plant photosynthesis processes, which can result in reduced plant sizes and impaired reproductive and immune system functions. As plants and marine organisms store large amounts of carbon in their cells, changes in marine and plant life cycles ultimately affect the carbon and energy cycles that support the Earth's ecosystems.