This causes a type of rapid deacclimation. When the sun sets, the deac-climated leaf tissue freezes rapidly. Ice crystals form in the individual cells within the leaf, rupturing and killing them. The effect is death of leaf tissue, particularly those leaves oriented toward the afternoon sun. The leaves on the outside of the plant, and especially those on the south and southwest side, will be most affected.
Damage is often most severe on leaves that are perpendicular to the sun's rays.
Plants vary in their susceptibility to sun scald. Wind and sun, alone or in combination, can damage evergreens because they cause the plants to transpire or lose water through their leaves. The water is not replaced because the roots cannot pick up water in cold or frozen soil. The leaves turn brown, starting with brown edges or needle tips and progressing between the veins or down the needles. The most severe damage will be on tissue farthest away from the veins, such as leaf edges, leaf tips and tops of plants.