Andy Greener wrote: > On 9 Jan 2009, at 10:08, Steve Heaven wrote: > >> On Fri, 2009-01-09 at 09:52 +0000, Andy Greener wrote: >> >> >>> Probably, but we can still have a bit of fun debating the thermal >>> transmission properties of a narrow lock (Wheaton Aston). Does more >>> warm water get through a lock with or without a boat in it, and what >>> about wide/broad locks? Does length matter? ;-) >> >> >> A lock certainly does have a effect on the freezing of the water in >> the >> vicinity. >> Last weekend the S&W in the Kidderminster area was frozen hard up to a >> depth of 15-25mm. >> The water above Caldwall lock was frozen right up to the top gates. >> The >> lock was full and completely frozen. However below the lock was ice >> free >> for a distance of about 40-50 feet. I guess that was due to the >> movement >> of the water from the flow through the leaky bottom gates. > > > Hmm, kinetic energy -> heat - this gets better! So the area of clear > water below the lock has a relationship to the potential energy > 'stored' in the pound above and the leakiness of the gates :-)
I noticed last week on the Middlewich Branch that the ice was considerably thicker and less uniform on the "upstream" approaches to bridge holes. I thought this may have been due to the broken ice "floes" drifting downstream during the day and getting clogged up as the canal narrowed above the bridge, then freezing into the new ice the following night. Andrew
