A number of factors can lead companies to close stores. One is mergers and acquisitions activity. As organizations join forces under a single umbrella, locations that once competed for sales can become redundant, leading to store closings.
There are 3 types of ultraviolet (UV) rays: 1  Ultraviolet A rays (UVA) make up most of the sun's natural light. They can penetrate deep into the skin, causing wrinkles and premature aging of the skin.  Ultraviolet B rays (UVB) are the main cause of sunburn. They are nearly 1,000 times stronger than UVA rays.
The ultraviolet (UV) rays that cause sunburns come in two forms. UV-A and UV-B. These rays, like all electromagnetic radiation, come in waves at specific frequencies. UV-A has wavelengths between 315-400 nanometers.UV-B wavelengths are between 280-315 nanometers.V-A and UV-B. These rays, like all electromagnetic radiation, come in waves at specific frequencies. UV-A has wavelengths between 315-400 nanometers. UV-B wavelengths are between 280-315 nanometers.