How does the national weather service monitors an approaching hurricane.

places of higher salinity. there are parts of the ocean where hardly any rain falls but warm dry winds cause lots of evaporation. this evaporation removes water – when water vapour rises into the atmosphere, it leaves the salt behind, so the salinity of the seawater increases. this causes the seawater to become denser.

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.