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Index of Subjects --Apple-Mail-77-387466870 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Hi Joan. On 26-Jan-07, at 7:52 AM, Joan Czapalay wrote: > Thanks to David, Chris, Steve and all on the Coriolis effect! This > thread is why I miss naturens, when I have to go off the chatline > to catch up on other things (job, children, and volunteer duties). > I have been a victim of mis-information for years. When flying over > the equator a number of years ago, I spent some time in the > washroom, trying to determined the moment when the vortex in the > sink would change direction! Thanks to your notes, I have been > reading up on this, and as Chris alerted me, the force is so small > that it plays no role in determining the direction of rotation of > water in a draining sink. > The effect is observable however, in long-lasting vortices, hence > the air flowing around a hurricane spins counter-clockwise in the > northern hemisphere and clockwise in the southern hemisphere. I recall reading about an experiment to try and detect the Coriolis effect on a smaller scale. Researchers took a very large volume of water (something on the order of a large swimming pool in volume). They let it sit for several weeks in a temperature controlled environment so that all thermally induced and other circulation in the pool ceased. Then they opened up a tiny pin-holed sized aperture in the bottom which allowed the water to very slowly drain. I think it took on the order of a couple of months to empty the pool and towards the end they were able to detect very slight Coriolis deflections in water. In any event, such a situation is very far removed from the (comparatively) huge forces that are at play in swirling water in sinks or toilets that would eclipse (by several orders of magnitude) the Coriolis effect in those situations. > Now, I must find out about the direction of turning on bindweed > plants. Is there a pattern?? Cheers, Joan This spiraling growth form of plants is called chirality. Most plants that grow in this way spiral counterclockwise although there are a few that spiral clockwise. Whichever way they turn, the direction is intrinsic to the plant species and under normal circumstances nothing can induce them to spiral in the opposite direction. This "circumnutation" as the growth is called, takes place via a so-called "thigmotactic response," which is a stimulus that allows the plant to sense its support and wrap around it. As it begins to helix around, the thigmotactic response releases hormones that make the cells on the opposite side of the growing stalk elongate and wrap around its support. This growth form seems to have a biochemical basis since researchers have been able to change the chirality of a plant species by administering depolymerizing drugs that break long polymers into shorter ones. A couple of genes called Lefty1sprl and Tornado2 have been identified as being associated with the generation of chirality. Having said that I don't know that the exact mechanism of this in plants is really understood (let me know if you can find something!) or what the ecological or evolutionary significance of it is. Some researchers (based on experiments on the growth of mosses in outer space done on the ill-fated Columbia mission, which miraculously survived the crash!) have speculated that a spiral is a very efficient way of spreading growth over a wide area. This could ensuring that space was optimally filled without parts of the plant crossing over each other and blocking light from filaments beneath. For an account of the moss experiments on the Columbia take a look at: http://www.bioedonline.org/news/news.cfm?art=1536 http://weboflife.nasa.gov/currentResearch/currentResearchFlight/ spaceSpirals.htm Cheers! Chris _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _. Christopher Majka - Nova Scotia Museum of Natural History 1747 Summer Street, Halifax, Nova Scotia, Canada B3H 3A6 (902) 424-6435 Email <c.majka@ns.sympatico.ca> _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _. --Apple-Mail-77-387466870 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 <HTML><BODY style=3D"word-wrap: break-word; -khtml-nbsp-mode: space; = -khtml-line-break: after-white-space; ">Hi Joan.<DIV><BR><DIV><DIV>On = 26-Jan-07, at 7:52 AM, Joan Czapalay wrote:</DIV><BR = class=3D"Apple-interchange-newline"><BLOCKQUOTE type=3D"cite"><DIV = style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; = margin-left: 0px; ">Thanks to David, Chris, Steve and all on the = Coriolis effect! This thread is why I miss naturens, when I have to go = off the chatline to catch up on other things (job, children, and = volunteer duties).</DIV><DIV style=3D"margin-top: 0px; margin-right: = 0px; margin-bottom: 0px; margin-left: 0px; ">I have been a victim of = mis-information for years. When flying over the equator a number of = years ago, I spent some time in the washroom, trying to determined the = moment when the vortex in the sink would change direction! Thanks to = your notes, I have been reading up on this, and as Chris alerted me, = the<SPAN class=3D"Apple-converted-space">=A0 </SPAN>force is so small = that it plays no role in determining the direction of rotation of water = in a draining sink.</DIV><DIV style=3D"margin-top: 0px; margin-right: = 0px; margin-bottom: 0px; margin-left: 0px; ">The effect is observable = however, in long-lasting vortices, hence the air flowing around a = hurricane spins counter-clockwise in the northern hemisphere and = clockwise in the southern hemisphere.</DIV></BLOCKQUOTE><DIV><BR = class=3D"khtml-block-placeholder"></DIV><DIV>I recall reading about an = experiment to try and detect the Coriolis effect on a smaller scale. = Researchers took a very large volume of water (something on the order of = a large swimming pool in volume). They let it sit for several weeks in a = temperature controlled environment so that all thermally induced and = other circulation in the pool ceased. Then they opened up a tiny = pin-holed sized aperture in the bottom which allowed the water to very = slowly drain. I think it took on the order of a couple of months to = empty the pool and towards the end they were able to detect very slight = Coriolis deflections in water. In any event, such a situation is