Relative humidity is the amount of water vapor present in air at a given temperature. Relative humidity depends on the temperature and pressure of the surrounding. The relative humidity is the ratio of the amount of water vapor in the air at a given temperature to the maximum amount of water vapor the air can hold at that given temperature, it is usually expressed in percentage.
It was the imperial palace of China for 492 years (1420–1912). It covers 0.72 sq km (0.28 sq mi), of which 15 hectares (38 acres) are floor area. It has 980 buildings in over 70 palace compounds, with over 8,700 rooms.
