Specific gravity意思

"Specific gravity" is a term used in various scientific fields, particularly in physics and chemistry, to describe the relative density of a substance compared to the density of a reference substance, usually water. The specific gravity of a substance is the ratio of its density to the density of water at a standard temperature, typically 4 degrees Celsius (39.2 degrees Fahrenheit).

For example, the specific gravity of gold is about 19.3, which means that gold is about 19.3 times more dense than water. The specific gravity of a liquid, such as ethanol, is used to determine its purity, and in meteorology, the specific gravity of air is used to calculate air density, which is important in understanding atmospheric pressure and wind patterns.