Helpful Data Hacks

As discussed in Water: Density vs Temperature and Salinity , the density of water changes as a function of thermodynamic properties like temperature and pressure.  Since density and volume have a simple inverse relationship, the volume of water also changes as those properties vary.  One commonly studied instance of this is the Coefficient of Thermal Expansion: the rate at which a substance's volume changes as the temperature changes and pressure is held constant.  For Water this Coefficient is particularly interesting because it starts off negative (volume decreases as you increase temperature) and then transitions to positive (volume increases as you increase temperature). Unfortunately, finding high-accuracy values for this Coefficient as a function of Temperature and Salinity on the internet proved difficult.  However, since we already did research and found high-accuracy values for Density we can use that data to numerically det...

Like all substances, water changes density as a function of thermodynamic properties like temperature and pressure.  For most substances, as you decrease the temperature, the density will increase.  This makes some logical sense: temperature is just a measure of the typical kinetic energy of the water molecules, and if you decrease the temperature then they will have less energetic collisions and spread out less.  Water behaves this way for most temperatures (4 - 100) ℃, but when you decrease the temperature below 4 ℃ the density decreases rather than increases.  It continues to decrease slowly until you reach 0 ℃, at which point water freezes into ice and the density decreases by nearly 10%.  This is a well known and studied property of water, and the reason icebergs float with 10% above the surface of the water and 90% below.  However, this behavior is not true for all types of water.  In particular, when you start dissolv...