pressure step, the difference in altitude between two points along the same vertical, expressed by the difference in atmospheric pressure, measured in units of 1 millibar (1 millibar = 100 newtons per m2). The barometric step increases with decreasing pressure. Therefore, it increases with increasing altitude. At sea level, at a standard pressure of 1,000 millibars and air temperature of 0° C, the barometric step is close to 8 m for every millibar. At an altitude of 5 km, where the pressure is approximately twice as low as at sea level, the barometric step is approximately 15 m for each millibar. The barometric step increases by 0.4 percent for every degree of temperature rise. The barometric step is used in barometric leveling.