WOOD HEATED TO HIGH TEMPERATURES PARTICLES FORMATION AS A RESULT OF GROUND LIGHTNING DISCHARGE INFLUENCE ON CONIFEROUS TREE TRUNK

Probably three scenarios of influence of ground lightning discharge current on a tree: 1) as a result of Joule heat emission occurs having warmed up and the subsequent ignition of a tree trunk; 2) there is a tree trunk warming up to similarly first variant and surface layers of tree dispersion to formation heated up to high temperatures particles and their subsequent loss on forest fuel layer in vicinities of a trunk and, as consequence, its ignition; 3) the discharge current spreads in root structure of a tree with formation of spark discharges and the subsequent ignition of forest fuel layer. Research of the second variant of forest fire ignition development is of interest. Research objective — studying of influence volt-ampere characteristics of the discharge on processes of surface layers dispersion of trunk of a coniferous tree. The problem dares for the cylinder which models a tree trunk. The certain section of a trunk is considered. Process of a warming up of a tree by a ground lightning discharge before ignition is described by system of the non-stationary differential equations of heat conductivity. For the decision of the present problem it is necessary to consider also its intense-deformed condition heated up to heats of thin surface layer of wood of a trunk in which there is an intensive thermal emission under the Joule law. For an estimation of level of arising thermal pressure and deformations the model of its intense-deformed condition approved for conditions of heating of heatshielding materials is used. In work the basic laws of dispersion process of trunk wood as a result of its warming up under the influence of Joule heat emission in a subcrustal zone of a coniferous tree at a ground lightning discharge are presented. For various values of current and voltage of a ground lightning discharge conditions of wood dispersion are established. One of possible variants of surface forest fuel ignition as a result of heated particles loss formed in the course of it dispersion under the influence of thermal pressure is revealed.