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.
Ultraviolet (UV) light is light with higher frequency (lower wavelength) than visible light. UV light has frequencies ranging from 8*1014 to 3*1016 Hz (800 THz to 30 PHz) and wavelengths from 10-8 m to 3.8*10-7 m (10 nm to 380 nm). Prolonged exposure to UV light causes sunburn and can cause skin cancer.