lO SMITHSONIAN IMISCELLANEOUS COLLECTIONS VOL. IO3 



The leeward slope for the most i)art has long fnigerlike ridges which 

 may he as much as 15 miles in length and is much drier than the 

 windward slope. The trade winds hlow from the northeast and hit 

 the high wall of cliffs on the windward slope. The maximum rain- 

 fall resulting from the rising of the moisture-laden trade winds over 

 the mountain wall falls not on the crest of the range but leeward 

 of the summit. This is shown in table i, where a series of precipita- 

 tion records obtained from a station at Nuuanu Pali, at the summit 

 of the Koolau Range, shows a lower rainfall than at Luakaha, below 

 the summit of the range. At a still lower elevation the rainfall drops 

 considerably at the Honolulu United States Weather Bureau station. 

 Table i also shows a greater precipitation at stations on the windward 



Table i.— Annual precipitation records in the Koolau Range 



Precipitation in inches 

 Elevation 

 Station in feet 



Kaneohe 100 



Maunawili 250 



Waimanolo 25 



Nuuanu Pali 1,136 



Luakaha (upper) 1,028 



Luakaha (lower) 881 



Honolulu (U. S. Weather Bur.) 11 1 



Makapuu 570 



Kawaiiki • 1,185 



Opaeula i ,100 



Kawailoa 185 



side of the island, such as Kaneohe and Waimanolo, than at the 

 Honolulu station on the leeward side. Table i was compiled from 

 "Climatological Data," published by the United States Department of 

 Agriculture. 



Hosaka (1937) gives some interesting data on temperature, relative 

 humidity, soil moisture, and soil temperature in Kipapa Gulch, which 

 is in about the center of the Koolau Range. The general trend is a 

 decrease in temperature and an increase in humidity with increase 

 in elevation. The average annual rainfall taken over a period of 5 

 to 36 years in Kipapa Gulch is as follows : At 59.05 to 196.85 feet 

 (Haole Koa zone), 23.07 to 24.33 inches; at 377.28 feet (Haole Koa 

 zone) to 672.54 feet (Guava zone), 47.77 to 47.49 inches; at 738.16 

 feet (Koa zone), 79.05 inches; at 1,797.82 feet (Ohia zone), 

 199.01 inches. The atmospheric temperature records from March 19 

 to November 26, 1933, show an average temperature at 246.06 feet 



