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Appendix

Handbook of Yosemite National Park (1921)
by Ansel F. Hall

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APPENDIX

THE WEATHER CONDITIONS OF YOSEMITE
VALLEY

By Ansel F. Hall

One often reads praises and generalities about Yosemite climate and weather but, so far as the writer knows, no concise statement as to exactly what might be expected at any given time of year has ever been published. The accompanying table has been compiled from the U. S. Weather Bureau daily records for the past eleven years and the data summarized for each month. By examining this table one may determine with fair accuracy the conditions which will be encountered at the time of his visit. The following remarks, however, should be borne in mind.

Temperature. The Mean Maximum is the average of the hottest temperatures for each day during the month (generally about 2 p.m.). The Mean Minimum is the average of the coldest temperatures for each night during the month (generally about 3 a.m.). The Mean Temperature is the average temperature for the entire month. The Maximum Temperature is the hottest recorded temperature during the month and the Minimum the coldest recorded during the same period. The Greatest Daily Range is the greatest temperature change for any twenty-four-hour period during the month. The Mean Maximum and the Mean Temperature show very little variation between the different years, but the Mean Minimum varies considerably, especially in the late spring and summer months. The Greatest Daily Ranges for the different months fluctuate greatly in different years, sometimes as much as fifteen degrees, so this factor in the table is not as reliable for forecasting temperatures as are the other averages.

Precipitation. Rainfall is a factor which varies extremely in different years in both amount and frequency. The frequency is indicated in the horizontal column headed "Number of Days with .01 inch or more Precipitation"; it must be remembered in this connection that from May to October on days upon which rain does fall it is generally as short thunder showers.

Snowfall. Snowfall is the one climatic factor which shows the most variation from year to year. A light snowfall sometimes occurs in October and may be rather definitely expected in November, the first snow in five of the past eleven years having occurred during the latter month; during these two months the snow generally melts quickly. In December, however, one may reasonably expect permanent snow, for the records show that in all but three of the past eleven years Yosemite Valley has had a "white Christmas." The melting of the permanent snow is more definite and may be expected quite regularly between March 15th and 30th.

Clear Days. The number of clear, partly cloudy, and cloudy days per month is surprisingly the same from year to year and these figures in the table will closely approximate actual conditions for any month.

WEATHER REPORT SUMMARY, YOSEMITE, CALIFORNIA—AVERAGE FOR ELEVEN YEARS (1909 TO 1919 INCLUSIVE)

TABLE OF LAKES IN YOSEMITE NATIONAL PARK WITH FISHING NOTES

¹ = Outside park boundaries.

Besides the lakes listed above (112 in the Park and 10 just outside) the U. S. G. S. "Topographic Map of Yosemite National Park" shows 317 other unnamed lakes—mostly small—within the Park. The total number of lakes within the Park is 429.

TABLE OF STREAMS IN YOSEMITE NATIONAL PARK WITH FISHING NOTES

¹ = Outside park boundaries.

THE IDENTIFICATION OF TREES

In using the following key the trees are eliminated by groups until the species is finally determined. For example: We may first examine the leaves to determine whether they are in bundles or arranged singly on the branchlets; this will eliminate the large group "I" or "II." If the tree falls in group "I" we then determine whether there are 5, 3, 2, or 1 needles in a sheath; this will put the tree in class "A," "B," "C," or "D." If the species falls in class "A" it may be further traced by comparing the characteristics listed under subdivisions "1," "2," and "3"; these will determine the species.

KEY TO THE CONE-BEARING TREES OF
YOSEMITE NATIONAL PARK

(All have needle-like, awl-like, or scale-like leaves)

I.—Leaves in bundles with a sheath around the base (Pines)

A—Needles in bundles of 5 (White Pines)

1—Cone large (12 to 24 in.). Bark red-brown, in large plates, and flaky. Alt. 4000 to 7000.

SUGAR PINE . . . Pinus lambertiana

2—Cone medium (6 to 10 in.). Bark dark gray and in small 5-sided plates. Alt. 7500 to 9500.

WESTERN WHITE PINE . . . Pinus monticola

3—Cone small (about the size of a hen’s egg) and hard. Bark white and smooth. Alt. 9000 to 11,000.

WHITE BARK PINE . . . Pinus albicaulis

B—Needles in bundles of 3 (Yellow pines)

1—Foliage silver-gray. Small or medium-size tree, generally branching into several main trunks. Cones large (5 to 8 in.), heavy, and armed with stout hooks. Alt. only below 3000.

DIGGER PINE . . . Pinus sabiniana

2—Foliage green. Tree large and generally with but one main trunk. Bark in large plates and flaky. Alt. 2000 to 8000.

(a)—Cones 2 1/2 to 5 1/2 in. long. Foliage green. Bark yellow-brown.

WESTERN YELLOW PINE . . . Pinus ponderosa

(b)—Cones 5 1/2 to 11 in. long. Foliage blue-green. Bark reddish brown. Generally at higher altitudes than western yellow pine.

JEFFREY PINE . . . Pinus jeffreyi

C—Needles in bundles of 2. Cones small (3/4 to 2 1/2 in.). Small tree (average 70 ft. tall and 2 ft. in dia.). Bark purple-gray and in flakes (not plates).

LODGEPOLE PINE OR "TAMARACK" . . . Pinus contorta

D—Needles one in a sheath. Cones small (2 to 3 in.) but seeds large. Tree small. Occurs entirely on eastern slope of Sierra Nevada except one tree in Pate Valley.

PINYON OR NUT PINE . . . Pinus monophylla

II.—Leaves not in bundles.

A—Leaves linear (i.e., needle-like.) Bark never fibrous or stringy.

1—Fruit a cone.

(a)—Cones erect and occur only near tops of trees. Leaves without petioles (leaf stalks). (Firs)

I—Bark of old trees gray and deeply furrowed. Needles on lower branches spread flat (2-ranked). Alt. 4000 to 8000.

WHITE FIR . . . Abies concolor

II—Bark of old trees red and roughened by vertical and transverse fissures. Needles all around branchlets and curved up. Alt. above 7000.

RED FIR . . . Abies magnifica

(b)—Cones pendent. Leaves with petioles.

I—Cone medium sized (2 to 4 in.) and with trident-shaped bracts sticking from between the scales. Tip of tree erect. Alt. 3000 to 6000.

DOUGLAS FIR . . . Pseudotsuga taxifolia

II—Cone small (i in.) and without exserted bracts. Tip of tree drooping. Alt. only above 8500.

MOUNTAIN HEMLOCK . . . Tsuga mertensiana

2—Fruit a drupe (like a plum) with a kernel much like a nutmeg when dried. Needles sharp-pointed and two-ranked. Small tree occurring in the canyon of the Merced only below Cascade Falls.

CALIFORNIA NUTMEG . . . Tumion californicum

B—Leaves scale-like or awl-like. Bark of all older trees fibrous and stringy.

1—Fruit a blue berry (really a modified cone). Leaves scale-like and closely pressed around twigs. Spray round. Inhabits open rocky sites above 7000 ft. alt.

WESTERN JUNIPER . . . Juniperus occidentalis

2—Fruit a true cone.

(a)—Cones medium size (1 1/2 to 3 in.) and with many scales. Needles of lower branches awl-like. Mature trees very large. Occurs only in scattered groves, the nearest of which is 17 1/2 miles from Yosemite.

GIANT SEQUOIA . . . Sequoia gigantea

(b)—Cones small (i inch or less) and with only 5 (apparently 3) scales. Needles scale-like and decurrent (i.e., with a portion of their bases fastened along the branchlets). Trees up to 5 feet in diameter. Spray flattened. Occurs abundantly in Yosemite Valley and up to 8000 ft. alt.

INCENSE CEDAR . . . Libocedrus decurrens

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