Low-pressure area This generates a steady wind blowing toward the land, bringing the moist near-surface air over the oceans with it. Similar rainfall is caused by the moist ocean-air being lifted upwards by mountains, surface heating, convergence at the surface, divergence aloft, or from storm-produced outflows at the surface. However the lifting occurs, the air cools due to expansion in lower pressure, which in turn produces condensation. In winter, the land cools off quickly, but the ocean keeps the heat longer due to its higher specific heat. The hot air over the ocean rises, creating a low-pressure area and a breeze from
High-pressure steam locomotive High-pressure steam locomotive A high-pressure steam locomotive is a steam locomotive with a boiler that operates at pressures well above what would be considered normal. In the later years of steam, boiler pressures were typically . High-pressure locomotives can be considered to start at , when special construction techniques become necessary, but some had boilers that operated at over . Maximising the efficiency of a heat engine depends fundamentally upon getting the temperature at which heat is accepted (i.e. raising steam in the boiler) as far as possible from the temperature at which it is rejected (i.e. the steam when