Volcanoes erupt when hot, molten rock called magma builds up beneath Earth's surface and pressure forces it upward through cracks in the crust. When the magma reaches the surface, it erupts as lava, ash, and gases.

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Ocean tides are caused mainly by the gravitational pull of the Moon and the Sun on Earth's oceans. The Moon has the strongest effect because it is much closer to Earth than the Sun.

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A rainbow forms when sunlight passes through water droplets in the air, bending and reflecting inside the droplets to split white light into its component colors. The observer must have the sun behind them and water droplets in front of them to see a rainbow.

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Lightning forms when ice particles in storm clouds collide and create electrical charges that separate, building up until the charge difference becomes so large that it causes a giant spark between the cloud and ground. This spark is what we see as lightning.

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The ocean is salty because rivers and rain dissolve minerals from rocks and soil, carrying them into the sea over millions of years. These minerals, primarily salt, accumulate in the ocean and cannot easily escape, making the water increasingly salty.

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