>OK. I've taken the bait. What's a "lake turn" ? And why would a lake >want to do that sort of thing ? Cooler water is more dense (actually, water is most dense at 4 deg C, decreasing in density when colder or warmer than this). Thus, most lakes are stratified with a lower more dense, cooler layer (the hypolimnion) and an upper less dense, warmer layer (the epolimnion). The boundary between these two layers is called the thermocline. The depth of the epolimnion grows during the warmer months. The density gradient resists wind-induced vertical mixing (thing of layers of oil and water). In the fall, the cooling of the epolimnion often results in the lake "turning over" --- this happens when the surface layer cools to the point where it is colder (read more dense) than the lower layer. In cold climates, the cooling of the surface water in spring associated with ice melt can produce another turn-over --- water at the bottom of the lake will be near 4 deg C; the melting ice cools the surface water to near this temperature; the lack of temperature stratification allows a wind-induced turnover (there isn't much resistance to vertical mixing because of the lack of stratification). See http://wow.nrri.umn.edu/wow/under/primer/page5.html for a more detailed description. Brian Curtiss *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Sat Jul 06 2002 - 11:35:05 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:30:53 PDT