Physics
Lightning is produced when

Clouds strike against impurities in air and the friction burns up these impurities
Strong opposite charges in different clouds break down the resistance offered by the intervening air
Water vapour produces electricity in the clouds
Similar charges of electricity rush towards each other and then get repelled

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Physics
It takes much longer to cook food in the hills than in the plains, because

n the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time
in the hills the humidity is high and therefore a lot of heat is absorbed by the atmosphere leaving very little heat for cooking
in the hills the atmospheric density is low and therefore a lot of heat is lost to the atmosphere
due to low atmospheric pressure on the hills, the water boils at a temperature higher than 100oC and therefore water takes longer to boil

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