radiational budget from the left columns of table h, the remaining values 

 of horizontal plus evaporative and sensible heat change are found in the 

 right columns of table h. This procedure is allowable, because heat 

 exchange is calculated only for daylight hours, so that effects of con- 

 vection are effectively eliminated. The assumption has been made that 

 the coefficient of absorption given in reference 6 is accurate for the 

 mid-iitlantic data used in this report. 



Table k 



CALCULATION OF HOURIZ HORIZOI^HIAL AIID^AffiRTICAL HEAT EXCHANGE FOR CLEAR SKIES 



(gm cal/cm'^/hr) 



Horizontal Plus Evaporative and Sensible 



Net After Removal of Absorption Heat Exchange 



Q^fl 



Hour 



(z) 



0'-20' 



20 '-to' 



4o'-6o' 



60 '-80' 



80 '-100 • 



0'-20' 



20 '-40' 



4o'-6o' 



60'-80' 



8o'-100' 



'•h 



-e'"© 



10-11 



-6.45 



-9.68 



-6.46 



-12.90 



-16.14 



-12.48 



-10.31 



-6.82 



-13.01 



-16.21 



-11.59 



-0.89 



11-12 



9.69 



6.46 



6.46 



6.46 



3.23 



-12.55 



4.13 



5.1'* 



6.05 



2.96 



4.57 



-17.12 



12-13 



25.83 



22.61 



22.60 



25.83 



22.61 



-18.32 



17.98 



19.98 



25.02 



22.08 



21.26 



-39.58 



13-lk 



41.98 



35.52 



29.06 



32.29 



35.52 



-5.08 



30.58 



26.27 



31.43 



34.95 



30.81 



-35.89 



U-15 



51.67 



41.98 



29.06 



35.52 



^ 41.98 



-2.26 



36.32 



25.86 



3'*. 53 



1(1.33 



34.51 



-36.77 



15-16 



1(8. H 



35.52 



25.84 



29.06 



35.52 



-0.35 



30.40 



22.95 



28.16 



3I+.93 



29.11 



-29.46 



16-17 



38.75 



25.83 



16.15 



16.15 



19.37 



-10.42 



20.67 



13.24 



15.25 



18.78 



16.98 



-27.40 



17-18 



25.84 



9.69 



3.23 



0.00 



0.00 



-15.53 



5.35 



0.78 



-0.76 



-0.50 



1.22 



-16.75 



18-19 



6.U5 



-9.68 



-12.91 



-16.14 



-19.37 



-22.51 



-12.72 



-14.63 



-16.67 



-19.72 



-15.94 



-6.57 



19-20 



-12.92 



-22.60 



-19.38 



-29.06 



-32.29 



-23.36 



-23.70 



-20.00 



-29.25 



-32.42 



-26.34 



2.98 



84.59 -207.45 



The horizontal, evaporative , and sensible heat exchange is rather 

 easily separated into horizontal and vertical components. The verti- 

 cal component of evaporative and sensible heat exchange will affect 

 only the layer from to 20 feet, "whereas horizontal heat exchange is 

 expected to affect all- layers nearly equally. An estimate of the hori- 

 zontal heat exchange is easily derived by averaging the heat exchange 

 for the four layers from 20 to 100 feet and is given in the column 

 labeled Q^i* The near equality of the values averaged is the argument 

 to support the accuracy of the absorption coefficient. Extending this 

 value into the layer to 20 feet, the amount of evaporative and sensi- 

 ble heat exchange is given in the extreme right column of table h. 

 The heat exchange values are shovm in figure k. Horizontal heat exchange 

 per 20-foot layer is generally positive and of the same order of magni- 

 tude as vertical heat exchange. The total evaporative-sensible heat 

 loss during the 10-hour period is 207"^ gm cal/cm2, but the total hori- 

 zontal heat exchange between and 20 feet is only b4.59 G''^ cal/cm2 

 because the direction of horizontal flow changes from output to input 

 during the 10-hour period. 



