How do lakes have rip currents?
Currents in lakes are caused by winds at the surface, temperature patterns and bathymetry, and the 'Coriolis force'. The load on the lake is proportional to a power of the wind speed, usually assumed to be 2, although of course it varies according to wind speed, wave conditions and atmospheric stability. A current is simply flowing water and can be caused by a number of factors. The location and strength of variable currents are much harder to predict.
Think of a lake as a giant bathtub, with strong winds pushing the water back and forth and gaining strength.
What causes the currents in a lake?
Knowledge of ocean currents has helped or hindered sailors in their efforts to cross the world's oceans for centuries. When the prevailing winds or the strongest winds are blowing in a particular direction, sediments are constantly moved in the same direction by the currents. Currents can be created by any combination of wind, waves, bottom conditions, beach slope, water temperature, man-made structures and natural runoff. Water current is the speed of movement in water, and ways to describe water current include its speed and direction.
On the open sea, the wind can push the water at different speeds for thousands of kilometres, and the downslope current can only be felt along the coast where the wind is blowing.
Are there strong currents in lakes?
Reduced buoyancy is the main cause of drowning, especially in lakes where swimmers may try to reach the far shore and the weakest in the group may be swept away and drown at the far end, far from the shore and out of sight of help. In horizontal flow with no horizontal pressure gradient and assuming no friction, water set in motion in the northern hemisphere will bulge to the right as the earth rotates from west to east. These can be strong and continuous or weak and sporadic; in terms of the ratio of the volume of inflow or outflow to the volume of the lake, the latter is the most commonly observed situation. Horizontal pressure gradients are important in lakes where there are significant inflows of water with a significantly different density than that of the surrounding lake or where there is significant differential surface heating.
Are currents dangerous in lakes?
The piers at Holland and Grand Haven state parks are particularly dangerous places on choppy days because structural currents can form in the water along the pier and waves breaking over the structure can push people off the pier into the lake. Guy Meadows, director of the Great Lakes Research Center at Michigan Technological University, has been researching dangerous currents and weather conditions for many years. These currents occur because many structures in the Great Lakes are solid to the bottom of the lake. People caught in a coastal current can find themselves far down the beach, far from where they entered the water.