1915] SMILEY—LAKE TAHOE REGION 275 
“chinook”? wind quite commonly melts the snow very rapidly 
Beside these general winds, mention should be made of the 
so-called “mountain and valley”? winds which reverse their move- 
ment twice daily, flowing down the valleys at nightfall and attain- 
ing considerable force when the valley narrows suddenly below, and 
flowing toward the summits when these have been heated by the 
morning sun. These winds are of moment in alpine plant dis- 
tribution as being probably among the most effective agents for 
extending the vertical limits of species. 
TABLE A 
MEAN MONTHLY AND ANNUAL TEMPERATURE (F.) 
p ‘ 
2 a ie # |g 5 : = 
Ss a4 By = 4 Sa se a. ae 5 
Bieta a ei ee Bee 2 eel ee 8 
S16 (8 SALA ete baie ia | 3 
Truckee 5818 ft.. .|25.3]28.3/32.9|40.0|48.4]57- 4/65 463.455.9145. 1|36.5|28.7/43.9 
Summit 7017 ft.. .|26.8 27-7|32.0135.9144.6/51.2/57.6|58.0/53.8|46.5/34.8/28.0]41.4 
Tamarack 8000 ft..|2r. 5|21. 7/26 .8/32.5|36.545.8|55.2 563/48. 1/39. 1/29.8)19.8/36.1 
TABLE B 
MONTHLY EXTREME TEMPERATURES* 
January February | March | April May June 
Summit..| 55\— 4] 35| 52|— 6| 53 6| 31\ 71|— 2| 301 85| 12\ 30] 82\ 281 43 
Tamarack] 49 ag 64 2 —25| 64} 64/—17| 54) 69/—14| 58] 81| 6] 46 80 18} 50 
July | August | September October November December 
Tamarac 86} 28) 47| 89] 27| 48) 88) 28) 48) 90] 20] 50] 69) + 8) 36 s5\— 5| si 
amarack} 86) 24] 47| 82| 30] 48| 80| 20| 50 76] 2) 49] 62/— 8] 48] 5 Bio 
*Under each month column gives the highest temperature ever recorded at got ~~ 
the second, the lace varidhoady and the third, greatest vac range ever recorded in the mo 
TABLE C 
TOTAL PRECIPITATION IN INCHES 1900-1913 
Nov. | Dec. |Annual 
| aay | June July | Aug. |Sept. ) Oct 
Jan. | Feb. |Mar. | Apr 
seo eri ea a 
Summit CN GEo a 13 58/3 aale wate 69\1 me RS 07|0.97/0.03|1.0 |o 85/4 94/6 24/40 98 
Tamarack .._. 16.85/5 08 4 74/3 3011 782.4 40/1.5 |0.31|/1.12/1.75|6.60/7.16|52.77 
