The map provides horizontal visibility forecast at 2 m above the ground. Visibility scale is on the right side of the page, measurement units are meters, m. Visibility decrease can disrupt the safety of transport, aviation, rail, marine and other vehicle traffic. If the visibility varies between 1 and 10 km, this phenomenon is called mist. If the visibility is less than 1000 m (1 km), it is called fog. Visibility may be reduced not only by fog or mist, but also because of intense precipitation (rain or snow).