Cold-morning elk


In the cold-morning air, an elk could see its breath. It is my guess that elk will have, at best, only a shallow grasp of the physics of the experience. 

The elk’s exhaling is producing steam fog. The process producing the condensation is identical to that which produces steam fog on the lake and the condensation trails (contrails) from the engines of high-flying jet planes. 

Condensation of water vapour results from either one of two different situations: vapour cooling (a consequence of the slope of the vapour-pressure curve); vapour mixing (a consequence of the shape of the curve).

Some writers find it tempting to explain the condensation by claiming that the exhaled vapour is cooled by encountering the cold air. Yet, the resulting mixture has undergone neither a net cooling nor a change in average moisture content. So, vapour cooling cannot be the origin of this condensation. 

However, vapour mixing, by itself, can produce condensation, particularly when there are great differences in the moisture and temperatures of the things being mixed, such as with contrails, steam fog over water, and seeing one’s breath.

An odd thing is that people watching the elk and breathing the same air did not see their own breaths. The implication is that the air exhaled from the elk’s lungs had the higher temperature (and moisture content). Possibly this occurs because these elk have just transitioned into their winter fur and were somewhat overheated.

A female elk breathes out steam fog.

A spike elk (a yearling male) breathes out.

Apparently, another youth has just taken up vaping.


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3 Responses to Cold-morning elk

  1. Dr. Doolittle says:

    The yearling has halitosis from the contorted nose of the woman beside him. Needs a dental plan and to drink matcha everyday.

  2. Christine Boyd says:

    I love these close ups and being able to see into their eyes. Thank you, Alistair.

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