FLORA OF TIBET OR HIGH ASIA. 131 
As in spring, so in summer, frequent and sudden changes of 
the weather occur—from heat to cold, from clear to cloudy ; and 
the state of the weather is so changeable that the inhabitants 
assert that each village in Tibet has its own weather. For in- 
stance, in the desert of Odontala (35° N. lat.), on the second of 
June, after a warm day, there arose a tempest with a heavy fall 
of snow, and after this the temperature fell to —9°4. On 
other days, at 1 p.m. the air-temperature in the shade was 33°2, 
and later 69°°6. In the open it was very hot, but any cloud 
rising in the clear sky caused a lowering of temperature and often 
snow or hail. On clear nights in July the temperature falls 
to 22°5. The sky is usually cloudy. Rain or snow falls 
every day; thunderstorms occur frequently. With the con- 
stantly falling rain the streams are quickly swollen. A river 
which in winter is scarcely 60 ft. wide, in summer spreads to a 
breadth of 300 ft.; the Murussu, with a bed 650 ft. wide in 
winter, becomes swollen in summer to 4800 ft., and at the same 
time the water, which in winter is clear and limpid, becomes 
thick and muddy. All Tibet becomes, as it were, an immense 
swamp. No journey whatever can be undertaken, because 
the only material by which, in these regions, a fire is kindled 
for cooking food, drying wet garments, and warming men 
numbed with cold—the dried dung of oxen—is softened and 
dissolves. 
Autumn is calm, dry, and rather warm ; tempests are rare, but 
when they do occur they arise in the west. The characteristics 
of summer seem to prevail throughout Tibet; but in the alpine 
region of tle Keria range rains were observed at least daily, and 
the mountains were enveloped in clouds. 
The province of Amdo, on the north-eastern boundary of 
Tibet, where the plains are more than 12,000 ft. high, rising 
above the course of the upper Hoangho and its affluent streams, 
has almost the same climate as Tibet. During the month of 
June, for instance, snow falls every day—indeed, according to 
the inhabitants, on some plains it never rains throughout the 
summer, but snows. Cold and storms prevail at the same time 
that spring is flourishing in the depth of the valleys. Never- 
theless a temperature of 80° was observed in July even on these 
elevated plains. In the deep river-valleys the air-temperature 1s 
cooler. A calm winter has a fairly copious snowfall, but even 
then only the northern slopes of the mountains are covered with 
Snow for any length of time; recent snow, even 1m February, 
