Friday, April 4, 2014

An Observational Oddity

Over the past few days, I have noticed a tendency for the temperature reported by the Alta-Collins observing station to plateau or even drop between about 11 am and 2 pm MDT, before rising again to even greater heights.

Why?  It happened even today with no precipitation around.


  1. Is there a shadow falling on it at that time?

  2. I would not expect a shadow at noontime, since it would be near overhead. but, perhaps it is part of the sensing gear which is over the sensor. What does that thing look like?

    1. This time of year, I think shading by Mt. Baldy does not occur at that site. There are, however, trees, and maybe that is playing a role.

  3. Clearing a hourly snow stake?

  4. he snow early in the morning. The snow sublimates to water vapor artificially cooling the air locally around the temperature transducer. At some point around 2pm the cooling offered by the sublimation gets overtaken by the heating of the air by the sun. Prior to 11am the sun isn't strong enough to heat the air so the cooling effect of sublimation is dominant.
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  5. it missed the first bit, not so smart phone. It's a complete guess but I was thinking in the morning the sun hitting snow causes it to sublimate cooling the air aroundthe transducer....then see above.

  6. Is there a wind graph to go with this one?