To say it has been cold would be a major understatement.  Yesterday Denver’s “high” temperature only reached -2 degrees and this morning DIA dropped to -17 degrees, one degree shy of the record low temperature for the date.  We decided to have a little fun with the cold weather in our Thornton backyard yesterday. 

One fun experiment to do when the temperatures is so cold is to demonstrate how boiling hot water instantly freezes when thrown in the air.  We figured it would make a great story for our work on Examiner.com and thought we would share the results here.

Your intrepid local weather geek conducted the experiment at a time when the sun was partially shining but the temperature was a bone chilling 1.4 degrees below zero.  For what it is worth, with a 9 mph wind that was generating a wind chill of 14 degrees below! 

The experiment is conducted simply using a pot of boiling water.  When the water is taken outside in zero degree or colder weather and thrown into the air, the water instantly freezes in a cloud of ice crystals. 

It is interesting to note that if you do this with cold water, you simply end up dumping water everywhere – it doesn’t freeze!  That of course begs the question, how does boiling hot water freeze faster than cold water?

This phenomenon actually has a name – the Mpemba effect – named after Erasto Mpemba, a student in Tanzania in the 1960s who studied it.  While it is named after Mpemba, other luminaries including Aristotle spent time analyzing it.

Dr. Joe Larsen, a chemist at the Rockwell Science Center in Los Angeles, explains that the hot water breaks into tiny droplets when it is thrown because it is close to being steam.  The heat from the small droplets freezes virtually instantly resulting in the ice crystal cloud. 

This doesn’t happen with cold water because it is thicker and in a closer to solid state (or at least not as close to turning to evaporative gas as the boiling water is).  As such, it doesn’t break up as easily and falls to the ground in blobs. 

So, for those of you with kids at home because school is canceled, you can now put their time to good use by conducting a science experiment in the cold!