Describe the three different types of lightning.
Ground-to-Cloud Lightning Ground-to-Cloud lightning(sometimes calledUpward-moving lightning) is adischargebetween cloud and ground initiated by an upward-moving leader originating from an object on the ground. Ground-to-Cloud lightning strikes are common on tall towers and skyscrapers. GC lightning can also be either positive or negative in polarity. Lightning that demonstrates upward branching is a clear indication of a ground-to-cloud flash, though some upward-moving lightning is branchless below cloud base. Intracloud Lightning The most common type ofdischarge- lightning inside a single storm cloud, jumping between different charge regions in the cloud. Intracloud lightning is sometimes calledsheet lightningbecause it lights up the sky with a 'sheet' of light. All or parts of the actual channel may be obscured inside the cloud, and may or may not be visible to an observer on the ground. Not to be confused withcloud-to-cloudlightning. Cloud-to-Ground Lightning - Positive A lightningdischargebetween cloud and ground initiated by a downward-moving, positively-charged leader. Abbreviated "+CG". Positive CGs are less common than negative CGs, and usually are associated with supercell thunderstorms and trailing stratiform precipitation regions behind squall lines. Positive cloud-to-ground lightning strikes can be identified visually and in photographs by their distinctive lack of branching (positive CGs occasionally will have branching at higher altitudes, but rarely near the ground). Positive CGs usually consist of only one return stroke, which is typically very bright and intense relative to other lightning activity in a storm. It is common for photographs of positive CGs to be overexposed unless the photographer has stopped the lens down significantly. Thunder from a positive CG is typically very loud, and many times sounds like a series of deep, low-frequency sonic booms. Cloud-to-Ground Lightning - Negative A lightningdischargebetween cloud and ground initiated by a downward-moving, negatively-chargedstepped leader. Abbreviated "-CG". Negative CGs are more common than positive CGs. Most of the lightning you can see striking the ground in a storm is of the negative cloud-to-ground variety. Negative cloud-to-ground lightning strikes can be identified visually and in photographs by their distinctive downward branching (aside from the portion of the channel very close to the ground, where upward leaders can be branched upward).
Negative CGs commonly consist of multiple "return strokes", which are additional pulses of current that illuminate the channel again and again. The first return stroke of a negative CG is usually the only branched one - the branches usually do not illuminate again in subsequent return strokes.
Positive CGs usually consist of only one return stroke, which is typically very bright and intense relative to other lightning activity in a storm. It is common for photographs of positive CGs to be overexposed unless the photographer has stopped the lens down significantly. Thunder from a positive CG is typically very loud, and many times sounds like a series of deep, low-frequency sonic booms. Cloud-to-Ground Lightning - Negative A lightningdischargebetween cloud and ground initiated by a downward-moving, negatively-chargedstepped leader. Abbreviated "-CG". Negative CGs are more common than positive CGs. Most of the lightning you can see striking the ground in a storm is of the negative cloud-to-ground variety. Negative cloud-to-ground lightning strikes can be identified visually and in photographs by their distinctive downward branching (aside from the portion of the channel very close to the ground, where upward leaders can be branched upward).
Negative CGs commonly consist of multiple "return strokes", which are additional pulses of current that illuminate the channel again and again. The first return stroke of a negative CG is usually the only branched one - the branches usually do not illuminate again in subsequent return strokes.
