SUNSHINE AND CLOUDINESS 35 



and diminishes the heat received by vegetation from the direct rays 

 of the sun. So also, acting as a screen, it prevents in a measure the 

 radiation of heat from the earth into space, and this materially tends 

 to modify and reduce the daily range of temperature, so that grow- 

 ing vegetation is not subject to as great cold as would otherwise 

 obtain during the night, nor on the other hand, does it receive the 

 full amount of solar heat by day. 



The average percentage of sunshine by seasons, with the aver- 

 age number of actually clear days, is as follows for the stations 

 named, as deduced from the records of the United States Weather 

 Bureau for a number of years : 



TABLE OF CLOUDS AND SUNSHINE IN CALIFORNIA. 



Winter. Spring. Summer. Autumn. 



^ c' .< c 2.< "o e 2.< "Off a< 



1^3 n n lij 3 fto q 3 f& rc i^ 3 n n 



8 IT. n %*'. ^ 8 *. * Jjj 8S; "3 



STATIONS. 2g' g-n> 25' 2-5' g-o 25' g- 



n f? ? " ? ? * ? ? l? 



Eureka 52 12 50 \2 72 21 64 33 



San Francisco 53 35 57 *38 57 29 65 42 



Los Angeles 66 49 56 36 69 39 75 54 



San Diego 61 37 51 26 54 24 63 38 



Red Bluff 55 38 62 42 88 80 78 70 



Sacramento 63 39 69 52 93 85 82 68 



Keeler 74 60 76 61 88 79 84 74 



Fresno 55 31 66 51 93 85 85 65 



Many useful deductions may be drawn from the above compil- 

 ation. It should be borne in mind, however, that the weather con- 

 ditions most favorable for vegetable growing are in some respects 

 different from those which minister to the perfection of fruits. 

 The fruit tree, with its roots deep in a moist soil, welcomes high 

 heat to mature its fruit. The perfection of the esculent falls far 

 short of the maturity of the plant and lies mainly in the measure and 

 tenderness of foliage, stem, immature fruit or fleshy root. These 

 are usually best attained at a degree of heat less than required for 

 fruit ripening. Again edible plants as compared with trees are 

 shallow-rooting and suffer in a very hot surface soil which a tree 

 escapes by penetration of tfie subsoil. The growth of winter vege- 

 tables is advanced by abundant sunshine during the rainy season: 



