Lake Erie, like other Great Lakes, does not experience the daily rise and fall of water levels driven by the Moon and Sun’s gravitational pull, which define oceanic tides. Instead, its fluctuating water levels are caused by various meteorological and physical phenomena.
Understanding Oceanic Tides
Oceanic tides are primarily a result of the gravitational forces exerted by the Moon and, to a lesser extent, the Sun on Earth’s vast bodies of water. The Moon’s gravity pulls on the side of Earth closest to it, creating a bulge of water. Simultaneously, a corresponding bulge forms on the opposite side of Earth, where inertia causes the water to essentially “lag behind” the solid Earth being pulled toward the Moon. As Earth rotates through these bulges, coastal areas experience two high tides and two low tides each day. The immense size of the oceans allows these differential gravitational forces to create noticeable and widespread water movements.
Why Lakes Lack Significant Tides
Lakes, including Lake Erie, do not exhibit significant gravitational tides because they are too small for the Moon’s and Sun’s gravitational forces to create a measurable differential pull across their surface. While gravity acts on all water bodies, the tidal force is the difference in gravitational attraction across an object. For a typical lake, the distance from one shore to the other is so short that the gravitational pull from the Moon and Sun is nearly uniform across its entire surface. This means there is no substantial difference in gravitational force to cause water to pile up or recede in a noticeable tidal pattern. Even the Great Lakes, though large, have tidal effects typically measured in mere centimeters, which are often masked by other environmental factors.
Lake Erie’s Water Level Dynamics
Water level changes in Lake Erie are primarily influenced by meteorological events rather than gravitational tides. One of the most significant phenomena causing rapid water level fluctuations is a seiche, which is a standing wave that oscillates within an enclosed or partially enclosed body of water. Seiches are often compared to water sloshing back and forth in a bathtub, and they can be initiated by strong, sustained winds or sudden changes in atmospheric pressure. Lake Erie is particularly prone to seiches due to its shallow depth and its southwest-to-northeast orientation, which aligns with common wind directions. Strong southwesterly winds can push water towards the eastern end of the lake (e.g., Buffalo), causing water levels to rise significantly there, while simultaneously lowering levels at the western end (e.g., Toledo).
When the initiating wind or pressure disturbance subsides, the piled-up water oscillates back across the lake, creating a sloshing effect that can last for hours or even days. This back-and-forth movement can lead to dramatic and rapid changes in water levels, sometimes by several feet, at opposite ends of the lake. For instance, a seiche in 2011 caused a water level difference of about 7 feet between Buffalo and Toledo, and historically, a 22-foot seiche was recorded in 1844.
Another factor influencing Lake Erie’s water levels is wind setup, where sustained strong winds physically push water towards one side of the lake. This creates a temporary slope on the lake surface, with higher water levels downwind and lower levels upwind. This phenomenon is closely related to seiches, as the wind setup can initiate the sloshing motion once the wind subsides. Atmospheric pressure also plays a role, with lower pressure systems allowing water levels to rise slightly and higher pressure systems causing them to fall. These dynamic, weather-driven events are often mistaken for tides by observers due to their periodic or noticeable nature.