Why did the temperature drop at dawn?

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Offline CZARCAR

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Why did the temperature drop at dawn?
« on: 12/12/2010 13:24:29 »
watching my digital outdoor thermometer this morn , I saw when the darkness got some light the thermo dropped from 5*f to 3*f......why?
« Last Edit: 12/12/2010 22:36:45 by chris »

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Offline chris

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Why did the temperature drop at dawn?
« Reply #1 on: 12/12/2010 22:40:15 »
My guess would be two possibilities:

1) The time when dawn breaks corresponds to the point at which the ground must have been unilluminated (and hence unheated) for the longest period of time (i.e. since the sun last set). Therefore one would expect the lowest temperatures to occur at some point around this time.

2) When the sun first begins to rise, the ground also begins to warm up; by convection this creates currents of rising warmer air, displaced upwards by falling cooler air. Therefore there may be a breeze initiated at dawn which brings in colder air and makes the temperature drop.

Chris
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Offline QuantumClue

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Why did the temperature drop at dawn?
« Reply #2 on: 12/12/2010 23:08:46 »
I'd say chris more or less hit it on the button.

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Offline CZARCAR

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Why did the temperature drop at dawn?
« Reply #3 on: 17/12/2010 13:34:18 »
monitored again yesterday & I could see the stars in the dark though not perfectly crispy night. Light W wind seeming not a constant wind.
5:30 am temp was 8.8*f
5:50---8.1
upper sky in the SW gaining vague light
6:20--------7.0*
6:40--------5.7*
day has lightened & i can see well outside
7:05---------5.9*
7:15------7.0*
8:30------9.1*