Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: CZARCAR on 12/12/2010 13:24:29

Title: Why did the temperature drop at dawn?
Post by: CZARCAR 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?

Title: Why did the temperature drop at dawn?
Post by: chris 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

Title: Why did the temperature drop at dawn?
Post by: QuantumClue on 12/12/2010 23:08:46

I'd say chris more or less hit it on the button.

Title: Why did the temperature drop at dawn?
Post by: CZARCAR 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*