It's mid-February and freezing in Denver, but the thermometer doesn't appear to show how cold it actually feels.

A stock photo shows a thermometer in cold weather. North Dakota, Minnesota, Montana and Wisconsin have extreme cold warnings in place ahead of an Arctic blast. MarianVejcik/Getty As of Friday at 4 ...

Another advantage of alcohol is that the freezing temperature of mercury is around -38F, so a mercury thermometer is not useful in extremely cold weather. Mercury can have usefulness over alcohol ...