A liquid cannot be squashed like a gas, but is not rigid like a solid and can flow and form drips. A liquid can be formed from a hot solid, when it melts, or from a cold gas, when it condenses. It can also form from a gas which is under great pressure. On the gas giants, gravity is very strong, and it presses the gas together.

This pressure is greatest near the centre of the planet, and it is here that the gas is squashed into a liquid. On the gas giants are oceans made of liquids, below the thick atmosphere of gas.

The pressures on the gases in the Earth's atmosphere are not so great as to squash them into liquids. The gas called water vapour in the air turns into a liquid by condensation.