Made by: Agata Skwara

UV radiation Ultraviolet (UV) light is electromagnetic electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3eV to 124 eV. It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. Although ultraviolet is invisible to the human eye, most people are aware of the effects of UV through the painful condition of sunburn, but the UV spectrum has many other effects, both beneficial and damaging, to human health. UV light is found in sunlight and is emitted by electric arcs and specialized lights such as black lights. It can cause chemical reactions, and causes many substances to glow or fluoresce. Most ultraviolet is classified as non-ionizing radiation. The higher energies of the ultraviolet spectrum from about 150 nm ('vacuum' ultraviolet) are ionizing, but this type of ultraviolet is not very penetrating and is blocked by air.

Types of UV radiation UVA was once thought to have a minor effect on skin damage, but now studies are showing that UVA is a major contributor to skin damage. UVA penetrates deeper into the skin and works more efficiently. The intensity of UVA radiation is more constant than UVB without the variations during the day and throughout the year. UVA is also not filtered by glass. UVA to 400 nm

UV-B UVB affects the outer layer of skin, the epidermis, and is the primary agent responsible for sunburns. It is the most intense between the hours of 10:00 am and 2:00 pm when the sunlight is brightest. It is also more intense in the summer months accounting for 70% of a person's yearly UVB dose. UVB does not penetrate glass UVB to 320 nm

UV-C UVC radiation is almost completely absorbed by the ozone layer and does not affect the skin. UVC radiation can be found in artificial sources such as mercury arc lamps and germicidal lamps UVC to 290 nm

Influence UV-B on plants In the experiment conducted in the greenhouse, the different doses of UV-B radiation applied to the two species Avena fatua and Setaria viridis induced changes in leaf and plant morphology. It was a decrease of plant height, fresh mass of leaves, shoots and roots as well as leaf area. Besides, it caused the leaf curling in both of the species. The significant differences between Avena fatua and Setaria viridis in the studied traits were mainly due to the tillering ability of the species. The content of chlorophyll varied considerably. The average values of leaf greenness (SPAD units) for oats were about 43 while for green foxtail 32, respectively. UV-B did not reduce leaf weight ratio, shoot dry matter, shoot to root ratio and leaf area ratio.

UV-B, respecFigure 1. Effect of radiation on the plants of Avena fatua (from the left 0, 4, 8 and 12 kJ/m2/d tively)

Figure 2. Effect of radiation on the plants Setaria viridis (from the left 0, 4, 8 and 12 kJ/m2/d UV-B, respectively

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