4. Snow avalanches, snow drifts and icings.

Snow avalanches, drifts and icings are the one of displays of spontaneous forces of a nature in a winter period. They result after the plentiful snowfalls, which can proceed from several hours to several days. The drifts, icing, avalanche influence the work of transport, power facilities, establishments of communication, agricultural objects etc. Snow collapses in mountains especially are dangerous when they have large destructive force and cause large material damage and human victims. The sharp differences of temperatures at snowfalls result in a covering of various surfaces by ice or wet snow. It causes infringement of communication lines, electric wires etc.

With occurrence of threat of snow drifts and icings services and formations get ready, the population is notified. Snow-cleaning works in cities first of all will be carried out on the basic transport highways, the work of vital objects of energy, heating and water supply is restored. The snow from a road must be removed to in leeward side. Engineering and snow-cleaning technique must be widely used. For realization of works all available transport, loading technique and population is attracted.

At an icing the contact networks of electric transport and communication lines are mostly exposed to destructive action catastrophe. In fighting with an icing three ways are used - mechanical, thermal and application of anti-icers. In the mechanical way the ice and snow is forced down from wires by the sticks, scrapers, attached on the sticks, cords thrown over wires. On contact networks of the electrified transport the specially equipped rail-buses and electric locomotives are used. At a thermal way the alternating or direct current.

On roads ice is chopped off or strewed by sand, slag, fine gravel first of all on sites with bad visibility and curves.

The fighting with snow avalanches has long-term character and must be organized by anti-avalanche services.

5. Lightning

In spite of the fact that the lightning rarely result in mass affection of the people (3 men on 100000 inhabitants annually, in Ukraine - about 1500 people annually, in the world-180000 annually; 4 times more people are injured), it is expedient to consider this spontaneous natural phenomenon.

Every second on a planet occur from 1500 up to 2000 thunder-storms, and the lightning flashes up to 6000 times per one minute. Force of electric current at storm can change from 10 000 up to 40 000 А. Air, through which a lightning passes, is heated up. Directly in the channel of passage of a lightning temperature of air reaches 30 000 0С at pressure from 10 up to 30 atm. The people being in 1 м from a place of impact of a lightning, can be thrown up into air. If the lightning gets in a object impregnated with a moisture, this moisture instantly boils and evaporates, that causes literally «explosion» of the trees, impregnated with it, brick walls etc. The capacity of similar «explosion» reaches from time to time capacity of 250 kg of TNT. As a result of impact of a lightning on the man the stop of heart, burns of a body, damage of a head and other vital organs can be observed. And, despite of it, only 25 % of the people which have experienced impact of a lightning, dies. At a thunder-storm the metal designs and products are dangerous, as they can be a conductor of an electrical current of a lightning on significant distances. Even such small pieces of metal, as jewelry , can serve a source of danger. The lightning kills the people directly, or affecting trees, and other subjects or structures.

The lightning can kill the man and indoors, if he is near metal (for example water pipe) or electrical network. The lightning frequently gets in the television aerial, therefore for decrease of risk of injury at a thunder-storm the TV set must be disconnected. The certain danger proceeds and from a telephone network. During a thunder-storm it is not necessary to hold metal subjects, even if it is an umbrella, gun, window frame etc. The fishers continuing fishing during a thunder-storm, are also in danger, as their rods are the points of lightning discharge.

In many cases it does not result in destruction, and it simply leads to burning of clothes. The most dangerous zone of the lightning affect is space around trees. Each fourth man, killed by a lightning, was hidden under a tree. The lightning strikes an oak more often, than other trees, as it is very much massive. If the lightning strikes in ground and the electric current reaches the man or animal, between legs there is a difference of potentials, that can result in death. The wet clothes will better conduct electricity, than human body, whereas the dry clothes are more dangerous to the man. The wet clothes removes an electrical charge from a body of the man, thus he can receive burns, but the internal organs will not be damaged.

To avoid a injury by a lightning, it is necessary to be guided by the following simply rules of behavior during a thunder-storm:

• To avoid open places and high trees;

• To hold legs together, and hands on the knees;

• If your clothes are damp, you can avoid serious traumas;

• If you are swimming, proceed to a coast immediately;

• It is better to be inside the car and to not touch its metal parts;

• If your hair is strongly electrified, if you hear rumble in rocks and metal structures which are taking place nearby, leave this place immediately.

It is necessary to render the first medical aid to the victims of lightning.

The revival taking place in a condition "of imaginary death" of an injured must be started, without waiting for arrival of the medical personnel. The basic measure of the first help is the realization of artificial breath. The artificial breath is necessary to carry out for a maximum long time before occurrence of independent breath or before obvious attributes of death. At a stop of heart do the indirect massage of heart.