Madalrõhk

Madalrõhk is the Estonian term for a low-pressure system in meteorology. It refers to a region where the atmospheric pressure at sea level is lower than in the surrounding air. The strength of a madalrõhk is often indicated by its central pressure, measured in hectopascals (hPa). Typical sea-level pressure is about 1013 hPa; a developing or mature madalrõhk usually has a central pressure below this value, and stronger systems can reach 980 hPa or lower.

Formation and structure: Low-pressure systems form when air rises, due to surface heating, terrain, or frontal activity. In mid-latitudes, they commonly develop as extratropical cyclones along the polar front and are steered by the jet stream. In tropical regions, low-pressure centers can organize into tropical depressions, tropical storms, or hurricanes. The rotation around the center depends on the hemisphere: counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

Weather and impacts: Madalrõhk is associated with cloudiness, precipitation, and wind. Rising air leads to condensation, cloud formation, and rain or snow, while winds converge toward the center and circulate around it. Weather can be unsettled, with fronts bringing temperature changes and precipitation; some patterns produce prolonged wet spells or storms.

Observation and significance: Meteorologists track madalrõhk by analyzing pressure fields on weather maps, using satellites, radar, and numerical models. Central pressure, along with the system’s size and depth, helps estimate potential wind speeds and rainfall. The term covers a broad range—from weak low-pressure areas to powerful extratropical cyclones and tropical cyclones.