![]() ![]() I won't repeat something provided in other answers. In your image above as well, you can see a lot of time is lost in looking for the route, whereas the return stroke just runs through the well defined channel and hence is much faster. The core temperature of the plasma during the return stroke may exceed 50,000 K, which makes it shine so bright. This massive flow of electrical current occurring during the return stroke combined with the rate at which it occurs (measured in microseconds) rapidly superheats the completed leader channel, forming a highly electrically-conductive plasma channel. ![]() But this flow unlike the flow from up has a well defined shortest route now. Once the stepped leader and the traveling spark have connected, then electrons from the cloud can flow to the ground, and positive charges can flow from the ground to the cloud. The traveling spark moves upward and eventually connects with the stepped leader. As the stepped leader gets close to the ground, a positively charged traveling spark is initiated on some tall object (trees, towers etc) on the ground. In this process it also branches out looking for the best route. ![]() It does so by traveling 50-100 meters at a time then stopping for about 50 microseconds, then traveling another 50-100 meters. But while moving towards the ground, it searches for the most efficient(minimum electrical resistance) route possible. First, a stepped leader is created at the base of the cloud which is a channel through which electrons in the cloud can travel to the ground. Once the voltage reaches a critical strength, the atmosphere can no longer act as an electrical insulator. Lightning happens when the potential difference between the clouds and the grounds becomes too large. Intra-cloud lightning is the most frequentlyĪppears that ground-to-cloud is possible, though normally only a result of a man-made object creating "unnatural" electric potential, and is the least common type of lightning. Is known as inter-cloud lightning, and when it occurs between areas ofĭiffering electric potential within a single cloud it is known as When it occurs between two separate clouds it Lightning discharges may occur between areas of cloud withoutĬontacting the ground. Might be worth also noting that cloud-to-ground is not as common as Cloud to cloud (CC) and Intra-Cloud (IC): The reason is that when cloud-to-ground strike approaches the ground, the presence of opposite charges on the ground enhances the strength of the electric field and the "downward leader" strike creates bridge for the "return stroke" this per the wiki page for Lightning. Source: National Severe Storms Laboratory So fast - in about one-millionth of a second - so the human eyeĭoesn't see the actual formation of the stroke. The return stroke that produces the visible flash, but it all happens These two paths meet, a return stroke zips back up to the sky. Upward streamer is sent out from the object about to be struck. A typicalĬloud-to-ground flash lowers a path of negative electricity (that weĬannot see) towards the ground in a series of spurts. Cloud-to-ground lightning comes from the sky down,īut the part you see comes from the ground up. Does lightning strike from the sky down, or the ground up? ![]()
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