High-pressure area easterly waves, and tropical cyclones that develop from them, across the ocean towards landmasses in the western portion of ocean basins during the hurricane season. The highest barometric pressure ever recorded on Earth was measured in Tonsontsengel, Mongolia on 19 December 2001. Wind flows from areas of high pressure to areas of low pressure. This is due to density differences between the two air masses. Since stronger high-pressure systems contain cooler or drier air, the air mass is more dense and flows towards areas that are warm or moist, which are in the vicinity of low pressure areas in advance
High-pressure area arctic air moves over an unfrozen ocean, the air mass modifies greatly over the warmer water and takes on the character of a maritime air mass, which reduces the strength of the high-pressure system. When extremely cold air moves over relatively warm oceans, polar lows can develop. However, warm and moist (or maritime tropical) air masses that move poleward from tropical sources are slower to modify than arctic air masses. In terms of climatology, high pressure forms at the horse latitudes, or torrid zone, between the latitudes of 20 and 40 degrees from the equator, as a result of air