Thunderstorms usually begin with small cumulus clouds, then rapidly develop, passing through the cumulus congestus stage before entering the mature cumulonimbus stage. It is a violent, severe, and rapidly changing weather phenomenon.
　　Outdoor enthusiasts should pay attention to the following points:
　　1Thunderstorms may occur when cumulonimbus clouds begin to accumulate and darken.
　　2Thunderstorms usually last a short time; stay calm, do not panic, and remain in a sheltered place.
　　The danger of lightning lies in its ability to penetrate objects and the human body, cause fires, and the thunder can rupture eardrums. Therefore, remember:
　　1Cars are often excellent lightning shelters; you can take cover inside a car during a lightning storm.
　　2The best shelters are caves, ditches, valleys, or clearings under clusters of tall trees.
　　3If you are in the open, crouch at a distance at least twice your height from an isolated tall tree.
　　4If you feel an electrical charge—such as your hair standing on end or your skin tingling—you may be about to be struck; immediately drop to the ground and assume a self-protective position.
　　5If taking shelter near an isolated protruding object, the top of that object should be at least15--20meters higher than your head.
　　6Stay away from vertical walls or cliffs, and avoid exposed mountain peaks, ridges, and flat, open terrain.
　　7Avoid ground fissures, patches of lichen, and overhanging rocks.
　　8As a last resort, you can sit among scattered rocks.
　　9In dangerous terrain, secure yourself with a rope.
　　10If taking shelter in a cave to avoid lightning, stay at least3meters away from all vertical rock walls to prevent electrical conduction injuries.