Source 
The Oceans 
(Reference No. 20) 
The Oceans 
(Reference No. 20) 
The Oceans 
(Reference No. 20) 
Diurnal Variation (°C.) 
0.39 (Average)* 
0.60 (Maximum)* 
0.00 (Minimum)* 
0.71 (Average)* 
1.10 (Maximum)* 
0.30 (Minimum)* 
0.93 (Average)* 
1.40 (Maximum)* 
0.60 (Minimum)* 
1.59 (Average)* 
1.90 (Maximum)* 
1.20 (Minimum)* 
0.2 to 0.3** 
0.4 to .06** 
0.20 in December 
0.69 in May 
Comments 
Observations in deep trop- 
ical water--overcast sky-- 
moderate to fresh breeze. 
Observations from deep 
tropical waters--clear sky— 
moderate to fresh breeze. 
Observations from deep 
tropical waters -- overcast 
sky--calm or light breeze. 
Observations from deep 
tropical waters--clear sky 
-- calm to light breeze. 
Deep water surface temper- 
ature observations in higher 
latitudes (Not the tropics). 
Diurnal variation at 50 
meters. 
Average values at 44 stations 
around the British Isles in 
coastal waters. 
*The numerical values given are believed to be somewhat in error; 
however, the influence of clouds and winds are evident. Cloudiness 
tends to decrease incoming radiation and reduces the amplitude of 
diurnal variation. Windiness tends to mix the surface layers distributing 
heat 
over a thicker layer, thereby reducing diurnal amplitudes in 
comparison with calm or light breeze conditions. 
**The diurnal variation of sea temperature is so small that it is of 
little importance to the physical and biological processes in the sea. 
The small variations are essential to the study of heat exchange between 
air and water. (From ‘‘The Oceans’’) 
12 
