Radiative Cooling / Cold Air Drainage

Here are a couple graphs illustrating the difference between the temp at my place (labelled RCB) and the airport here in Gander (YQX) on two different nights (Wed night and Thu night of this week). First night was cloudy (it cleared late, but remained breezy with cold-advection NW winds). Second night was clear with very light winds under a ridge. Interesting to watch how the first night temps fell roughly in parallel with each other. However the second night temps at the airport remained relatively constant, while the bottom fell off the thermometer at my place. Good thing the sun came up when it did!

For those unfamiliar, the airport is on a plateau, whereas I'm about 5 km away and 100 feet lower in elevation, much more susceptible to cold air drainage and radiative cooling under the right conditions.

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Thanks Rodney. Interesting comparison.

Very interesting Rodney. The same effect happens here as well. Often on calm, clear nights, the temperature will drop 4-7 degrees cooler at my house than many of the surrounding areas. It's interesting to see the places that cold air tends to pool up and collect.. they can be very small and isolated. Sometimes moving just a couple hundred meters away will bring you out of the inversion, and the temperature could be several degrees higher. I'll have to do up some comparisons of my own and post them here.

Radiational cooling at it's finest :D

This snapshot is as of 6:20am this morning. Temp of -21 at my plce, but most of the surrounding areas were -11 to -14. It's interesting to see how localized these cool pools of air can be.

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Nice. I see Sydney Airport bottomed out at -18.3° at the manned site but -16.1° at the nearby automatic station. Not quite sure how far apart they are, but they're pretty close. I only have their coordinates rounded to the nearest minute and they are both listed as at 46'10N, 60'03W, which implies they're approximately within a mile or so of each other.

The Stevenson screen and rain gauge for the manned station are next to the airport control tower, while the anemometer and auto station are located in the middle of the airfield, which is about a km south or southwest of the tower.

I'm still surprised at the vast differences in temps between such small areas. The low at my station was -21.1, however a privately owned station over in glacé bay only went down to -12.8 degrees. A privately owned station in Sydney bottomed out at -18.5, which was a little closer to what I observed here.