12-24-2008, 05:06 PM
BMURR,
I can see now that my wording may have been confusing and also could have hurt your feelings. My post was not directed at you personally but was intended to shock the readers into listening and understanding the risks. People were breaking through ice at Devils Creek and Mud Lake as I wrote that. It also looked scary for the weekend since several of the lakes had a thick blanket of snow and our forum members predicting safe ice -- based on weather forecasts and past temperatures.
Part of what I said was to help describe how to use the rule of thumb for ice formation so that people would not misinterpret. Ice formation is fairly straight forward. When the top interface temperature is less than freezing, ice forms. It thins when the interface temperature is above freezing. The rate of formation is a function of the temperature difference (or delta T). Snow acts as an insulator and the interface temperature becomes only slightly below freezing (say about +30 F) when you have two foot of snow and -30 F air temperature. Under these conditions, folks that only have experience with bare ice behavior draw false conclusions (and predictions) about how quickly ice will form based on previous years where the conditions were different.
As far as how thick ice needs to be before it is safe, one of the best answers can be found at the following web site;
http://www.fishandgame.com/icesafe.htm
The short answer is that ice is never "safe". The web site listed above recommends several safety measures that I described (and use) including "picks for life".
No hard feelings......
FR
[signature]
I can see now that my wording may have been confusing and also could have hurt your feelings. My post was not directed at you personally but was intended to shock the readers into listening and understanding the risks. People were breaking through ice at Devils Creek and Mud Lake as I wrote that. It also looked scary for the weekend since several of the lakes had a thick blanket of snow and our forum members predicting safe ice -- based on weather forecasts and past temperatures.
Part of what I said was to help describe how to use the rule of thumb for ice formation so that people would not misinterpret. Ice formation is fairly straight forward. When the top interface temperature is less than freezing, ice forms. It thins when the interface temperature is above freezing. The rate of formation is a function of the temperature difference (or delta T). Snow acts as an insulator and the interface temperature becomes only slightly below freezing (say about +30 F) when you have two foot of snow and -30 F air temperature. Under these conditions, folks that only have experience with bare ice behavior draw false conclusions (and predictions) about how quickly ice will form based on previous years where the conditions were different.
As far as how thick ice needs to be before it is safe, one of the best answers can be found at the following web site;
http://www.fishandgame.com/icesafe.htm
The short answer is that ice is never "safe". The web site listed above recommends several safety measures that I described (and use) including "picks for life".
No hard feelings......
FR
[signature]