What are Ekman spirals and how can we utilize them to control cloud movement?

And how can we incorporate seeding of the clouds and what is the best known agent for this ??What are Ekman spirals and how can we utilize them to control cloud movement?
There are different names for patterns in different materials. Eckman Spirals are the patterns found in wind. Because you can not see wind it is difficult to appreciate Eckman Spirals but a very similar effect is evident in water, these are known as Von Karman trials. To demonstrate these in water place a upright stick in a fast flowing stream, the patterns which are created are very similar to Eckman Spirals in wind.



Vagn Ekman 1874-1954 was an oceanography, who gave a theoretical description of the consequence of the Corriollis effect on ocean currents. He stated that surface currents are deflected to the right of the wind direction.



An understanding of Ekman's theories can be for useful in Permaculture. Either using it positively or avoiding its negative effects. Eckman's Effects are usually associated with stands of trees, or shelter belts. Wind approaching trees is compressed as it climbs above them, then the consequential drop in pressure on the lee of the trees creates a downward Ekman's spiral. This is a negative effect in terms of wind on crops because the wind is speeded up which results in crop damage. This is typically twenty times the height of the obstruction away.



A positive effect on a larger scale such as forests on mountainous regions is the increase in rainfall which we know is one of the major limiting factors in vegation growth.



Studies in Holland and Sweden reveal that forty percent of rainfall measured down wind of trees of more than forty feet tall is caused by the above effect.



A far more modest effect can be created by planting condensing trees such as lombard poplars. Moist morning air

condenses freely on cool branches.



In some desert regions it has been found that even hanging nets above collection gutters will collect enough moisture from the air to allow a modest amount of vegetation to flourish. Which in turn collects more moisture so you have more and more moisture. Plants are then facilitated in growing large enough to produce shade, thus reducing evaporation and making the whole area more moist.



Cloud seeding is a form of weather modification. In order for water droplets to form they require something to form a nucleus. This usually consists of dust particles blown into the air. It has also now been found that air pollutants make excellent nuclei.



I argue that Ekman spirals actually spiral down, therefore to see the clouds you would need to use thermals. Thermals are warm air rising from a well illuminated area such as cliffs and bare rock. Imagine the red indian stood on the cliff top doing his rain dance, thermals rising and large amounts of dust from the fire being carried by the thermals upwards into the air creating the required nuclei. It has also been noted that fine dust particles from tea plantations have a similar effect.What are Ekman spirals and how can we utilize them to control cloud movement?
Thanks - bella

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What are Ekman spirals and how can we utilize them to control cloud movement?
The Ekman spiral refers to a structure of currents or winds near a horizontal boundary in which the flow direction rotates as one moves away from the boundary. It derives its name from the Swedish oceanographer Vagn Ekman. The deflection of surface currents was first noticed by the Norwegian oceanographer Fridtjof Nansen during the Fram expedition (1893-1896).



The effect is a consequence of the Coriolis effect which causes objects to move to the right of applied forces in the northern hemisphere and to the left in the Southern Hemisphere. Thus when the wind blows on the ocean surface in the northern hemisphere, the surface current moves to the right of the wind. As the water at the surface pushes on water below it, this water moves yet further to the right of the wind, and so on. As the current deflects, the velocity becomes progressively weaker. The depth to which the Ekman spiral penetrates is determined by how far turbulent mixing can penetrate over the course of a pendulum day.[1]



The classic Ekman spiral has been observed under sea ice, but is not found in most open-ocean conditions. This is due both to the fact that the turbulent mixing in the surface layer of the ocean has a strong diurnal cycle and to the fact that surface waves can destabilize the Ekman spiral. Ekman spirals are, however, found in the atmosphere. Surface winds in the Northern Hemisphere tend to blow to the left of winds aloft.



I hope it helps!