Dagály

Dagály is the Hungarian term for the tide, the regular rise and fall of sea level caused by the gravitational forces of the Moon and the Sun. In everyday usage, dagály refers to the high-water phase, while the corresponding low-water phase is called apály. The tide is a global phenomenon affecting coastlines, harbors, and estuaries around the world, with local expressions varying by place.

The mechanism behind dagály involves the gravitational pull of the Moon and the Sun on the Earth’s oceans. On the side closest to the Moon, gravity creates a bulge, producing a high tide; on the opposite side, inertia creates another bulge. The Sun’s gravity also contributes, though less strongly. Most coastlines experience two high tides and two low tides within a tidal day (semidiurnal), though some regions have one high and one low tide per day (diurnal) or mixed patterns. The cycle between successive high tides is about 12 hours 25 minutes and varies with the Moon’s position, producing larger tides during spring tides (at full and new Moon) and smaller tides during neap tides (at first and third quarter).

Local variation is strong: tidal amplitude depends on coastline shape, bathymetry, and ocean basin geometry. Weather effects, such as winds and atmospheric pressure, can enhance or suppress tides and cause storm surges. Tides influence navigation, coastal engineering, sediment transport, and ecosystems, and they underpin tidal-energy concepts that exploit regular water movement for power.

In Hungarian, dagály is a standard term in geography, meteorology, and nautical contexts. Hungary, being landlocked, does not experience natural coastal tides, but the concept is described and studied as part of global tidal phenomena.