Editor’s note: As we continue to invite bloggers out there in the wild to compose our monthly Blogroll column, John Spevacek penned the March 2014 column.

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How cold is cold, and how big is a drop of liquid?

As I write this column on a cold mid-January morning, North Americans are finding out that the phrase ‘cold snap’ is terribly outdated and that we should be using ‘polar vortex’ instead to describe the cold air that dropped temperatures as much as 30 °C below normal. Nevertheless, using the speed of gas molecules — and even cars — to prove his point, Matt Strassler who blogs at Of Particular Significance suggests that maybe it really wasn’t that cold after all. Although you can’t disagree with the arguments he makes, the desire to put on an extra sweater before venturing outside remains very real. The discussion in the comments is also worth reading. Matt’s point, however, is that the cool-down was just a drop in the bucket.

Speaking of drops, Mike, who writes at the Amboceptor blog, recently took a look at what makes up ‘a drop’ and fractions-of-a-drop when they are described in experimental procedures. Focusing on a diagnostic test for typhoid that was first reported in 1910, Mike finds that descriptions such as ‘full-sized drop’, ‘half drop’ and ‘quarter drop’ led, unsurprisingly, to irreproducible results that prompted some testy debate in the medical literature of the day. The post concludes by noting that, “those of us with access to space-age technology like micropipettes should count our blessings.”

Lastly, pitch-drop experiments have been discussed extensively this past year, but Michael de Podesta of the Protons for Breakfast blog offers some unique thoughts about them. These include how timescales vary with the observer and how “although all the forces are all constant, the response is not. This is like many processes in nature, but it seems an especially apt analogy for climate change”. And polar vortices too.

Written by John Spevacek, who blogs at http://www.rheothing.com/.

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[As mentioned in this post, we’re posting the monthly blogroll column here on the Sceptical Chymist. This is the March 2014 article]