The negative charge of the cloud repels electrons on the surface of the earth.

Transcription

1 Lightning

2 Lightning Lightning is a very large static charge. How is this static charge created? A thundercloud can become became charged by friction. Due to high winds, air molecules can rub against water droplets or ice crystals in the cloud. The bottom of the thundercloud becomes negative compared to the top of the cloud, because of the unequal distribution of ice crystals. Large, positively charged crystals tend to be near the top and smaller, negatively charged crystals are near the bottom of of the cloud.

3 The negative charge of the cloud repels electrons on the surface of the earth.

4 Lightning Lightning is a very large static charge. How is this static charge created? A thundercloud can become charged by friction. Due to high winds, air molecules can rub against water droplets or ice crystals in the cloud. The bottom of the thundercloud becomes negative compared to the top of the cloud, because of the unequal distribution of ice crystals. Large, positively charged crystals tend to be near the top and smaller, negatively charged crystals are near the bottom of the cloud. The negative charge of the cloud repels electrons on the surface of the earth, causing the surface to be charged by induction. The strong attraction between the negative cloud and the positive surface of the Earth causes electrons to arc between the cloud and the Earth, creating a huge spark. The result is what we see as lightning.

5 There is a strong attraction between the negative cloud and the positive surface of the earth.

6 Lightning Lightning is a very large static charge. How is this static charge created? A thundercloud can become charged by friction. Due to high winds, air molecules can rub against water droplets or ice crystals in the cloud. The bottom of the thundercloud becomes negative compared to the top of the cloud, because of the unequal distribution of ice crystals. Large, positively charged crystals tend to be near the top and smaller, negatively charged crystals are near the bottom of the cloud. The negative charge of the cloud repels electrons on the surface of the earth, causing the surface to be charged by induction. The strong attraction between the negative cloud and the positive surface of the Earth earth causes electrons to arc between the cloud and the Earth, earth, creating a huge spark. The result is what we see as lightning.

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8 Lightning Lightning is a very large static charge. How is this static charge created? A thundercloud can become charged by friction. Due to high winds, air molecules can rub against water droplets or ice crystals in the cloud. The bottom of the thundercloud becomes negative compared to the top of the cloud, because of the unequal distribution of ice crystals. Large, positively charged crystals tend to be near the top and smaller, negatively charged crystals are near the bottom of the cloud. The negative charge of the cloud repels electrons on the surface of the earth, causing the surface to be charged by induction. The strong attraction between the negative cloud and the positive surface of the earth causes electrons to arc between the cloud and the earth, creating a huge spark. The result is what we see as lightning.

9 Lightning The rapid transfer of electric charge from object to another is called Electric Discharge.

10 Thunder A lightning bolt can reach temperatures of C (that s about six times the temperature of the sun s surface). This incredible temperature heats the air around the lightning bolt, causing the air molecules to move quickly. These fast molecules slam into slower molecules and produce a shock wave that we hear as thunder.

11 Lightning Strikes Lightning bolts strike the earth about million times a day. At any given time there are 2000 thunderstorms somewhere on Earth. earth. Every year, about 60 Canadians are struck by lightning. Six or seven of these people die. Number of strikes per km 2 per year Distribution of Lightning Strikes

12 Types of Lightning Not all lightning strikes the Earth. Most lightning strikes from cloud to cloud orwithin the cloud itself. Cloud to earth strike.

13 Types of Lightning Not all lightning strikes the Earth. Most lightning strikes from cloud to cloud orwithin the cloud itself. Cloud to cloud strike.

14 Lightning Rods Lightning can cause damage to homes and other buildings. When lightning strikes a building made of wood or brick, the electrons force their way through the material, causing friction, which leads to fire.

15 Lightning Rods Lightning can cause damage to homes and other buildings. When lightning strikes a building made of wood or brick, the electrons force their way through the material, causing friction, which leads to fire. To protect a building a lightning rod can be installed. The lightning rod is placed at the top of a building and is connected to the ground through a metal wire Ground wire directs electrons to the earth. Lightning rod receives the lightning strike.

16 How a lightning rod works. Th e ne g at i ve l y ch a rge d cloud repels electrons from the lightning rod making it positively charged (the rod is charged by induction). The electrons from the cloud a rc t o t h e r o d a s a lightning strike. The electrons are directed to the ground through a metal wire.