Creek (reservoirs) - the movement of water masses in reservoirs ( seas , lakes , reservoirs ). The main types of currents are: sewage (sometimes referred to as stock), wind, convection.
Content
Sewage
Sewage flows are associated with the influx of water from the tributaries and their exit through the closing target. That part of the sewage flow that passes without loss through any part of the reservoir is called a transit flow. Sewage flows occur in the presence of a longitudinal slope, that is, they are carried out under the influence of a gradient of hydrostatic pressure , so they can be called gradient .
Wind currents
Wind currents are formed under the influence of wind , while currents directed towards the wind and often covering only the surface layers of the reservoir are called drift. Reverse compensation currents, which are carried out under the influence of a skew of the water surface (wind- driven surge ), are also called gradient (or gradient wind); they most often cover the bottom layers of the reservoir. In the presence of a drift current and a gradient countercurrent on one vertical, they speak of a mixed flow. The flows associated with the difference in atmospheric pressure in individual parts of the reservoir are also called gradient.
Convection currents
Convection currents are caused by the density heterogeneity of water masses. If a stable density inhomogeneity is created in significant parts of the reservoir, leading to the appearance of a longitudinal pressure gradient, then stable compensation flows are formed that are gradient in nature. Vertical density heterogeneity leads to vertical convection , which transfers in the form of separate portions (vortices) of denser volumes of water down to the bottom, lighter - up. Density heterogeneity can be associated with thermal heterogeneity of water masses and the difference in the concentration of dissolved or suspended substances (bottom heavy flows).
The currents observed off the coast of water bodies can be distinguished under the common name of coastal and classified into alongshore, normal (to the coastline ) and complex, with longitudinal and normal components. The normal component of the current directed towards the coast always causes the reverse normal counterflow . An important role in the formation of coastal currents is played by wind waves, transforming and collapsing when approaching the shore and transmitting some of their energy to the current.
See also
- Circulations
- Sea currents
Literature
- Chebotarev A. I. Hydrological Dictionary. L., Hydrometeoizdat, 1978.