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Lightning Formation |
The sky is filled with electric charge. In a calm sky, the + and - charges are mixed up. Inside a thunderstorm, the + and - charges are separated into two sections. All of the + charges are at the top of the thunderstorm cloud. All of the - charges are at the bottom of the thunderstorm cloud. During a thunderstorm, the ground has a + charge. + and - charges are attracted to each other. The - charge at the bottom of the thunderstorm cloud wants to meet the + charge of the ground. The - charge of the cloud starts to rush toward the + charge at the ground. At the same time, the + charge rushes toward the - charge. It happens so fast that all we can see is a line of light. This is called lightning. |
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The sky is filled with electric charge. In a calm sky, the + and - charges are evenly interspersed thoughout the atmosphere. Therefore, a calm sky has a neutral charge. Inside a thunderstorm, electric charge is spread out differently. A thunderstorm consists of ice crystals and hailstones. The ice crystals have a + charge, while the hailstones have a - charge. The ice crystals are pushed to the top of the thunderstorm cloud by an updraft. Meanwhile, the hailstones are pushed to the bottom of the thunderstorm by its downdraft. Thus, the thunderstorm's + and - charges are separated into two levels: the + charge at the top and the - charge at the bottom. During a thunderstorm, the Earth's surface has a + charge. Because opposites attract, the - charge at the bottom of the thunder cloud wants to link up with the + charge of the Earth's surface. Once the - charge at the bottom of the cloud gets large enough to overcome air resistance, a flow of - charge rushes toward the earth. This is known as a stepped leader. The + charges of the Earth are attracted to this stepped leader, so a flow of + charge moves into the air. When the stepped leader and the + charge from the earth meet, a strong electric current carries + charge up into the cloud. This electric current is known as the return stroke of lightning and is visible to the human eye. |
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The sky is filled with electric charge. In a calm sky, the positive and negative charges are evenly interspersed thoughout the atmosphere. Therefore, a calm sky has a neutral charge. Inside a thunderstorm, electric charge is spread out differently. A thunderstorm consists of ice crystals and hailstones. The ice crystals have a positive charge, while the hailstones have a negative charge. The postively charged ice crystals are pushed to the top of the thunderstorm cloud by an updraft. Meanwhile, the heavy negatively charged hailstones are pushed to the bottom of the thunderstorm by its downdraft. Thus, the thunderstorm's positive and negative charges are separated into two levels: the positive charge at the top and the negative charge at the bottom. During a thunderstorm, the Earth's surface has a net positive charge. Because opposites attract, the negative charge at the bottom of the thunder cloud wants to link up with the positive charge of the Earth's surface. Once the negative charge at the bottom of the cloud gets large enough to overcome air resistance, a flow of negative charge rushes toward the earth. This is known as a stepped leader. The positive charges of the Earth are attracted to this stepped leader, so a flow of positive charge moves up through some elevated point, such as a tree or a telephone pole, and into the air. When the stepped leader and the positive charge from the earth meet, a strong electric current carries positive charge up into the cloud. This electric current is known as the return stroke of lightning and is visible to the human eye. The above process will occur three or four times, all within a few seconds. Normally the human eye cannot distinguish between all of the return strokes. |
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