But when the tragic incident occurs between those who are near or dear to one another--if, for example, a brother kills, or intends to kill, a brother, a son his father, a mother her son, a son his mother, or any other deed of the kind is done---these are the situations to be looked for by the poet.
When water is heated it expands. For example, water heated from 90Â°F to a thermostat setting of 140Â°F in a 40 gallon hot water heater will expand by almost one-half gallon.
The increase in volume (expansion) lowers the density of the warm water at the bottom, feeling less pressure from gravity, the warm water moves up and the cooler, denser water moves down to replace it. With convection, the particles in the material move, carrying thermal energy with them.