Descending from the plateau and entering a warmer region, the air lost some of its arctic coldness; nonetheless, in the ancient northern capital the chill struck into men’s blood. By day, a sun like tarnished brass shone without warmth through clouds of yellow dust. By night, the eyes saw nothing, but the dryness and smell of dust pinched the nostrils. The fur-coated foreigners (as was their birthright) blasphemed at the weather; the thin-clad, shivering coolies moved stoically about their business. Nightly in hovel and doorway, huddling in corners, some scores of the poor froze slowly to death.

Southward along the coast of China ran that river of air. Among the hills of Shantung it was still an iron-cold blast, but on the plain of the Yangtze its power was less. In Nanking and Shanghai the ice formed only in quieter, shallower pools.

The air at last swung away from the coast, and moved out over the sea; with every mile of passage across the water it grew more moist and temperate. Through a thinning yellow haze the sun pierced more warmly. Now the wind was no longer a gale, scarcely even a strong breeze. The polar fury was spent. But still, east by south, the river of air flowed on across the China Sea toward the far reaches of the Pacific.

4

In mid-afternoon the front of the Siberian air-mass was pushing slowly across the island-studded ocean which lies east of China and south of Japan. Its cold heavy air clung close to the surface of the water. Advancing thus as a northeasterly breeze, it forced backward the warmer, lighter air ahead of it, and occasionally pushed beneath this air vigorously enough to cause a shower.

This opposing and retreating air had lain, some days previous, over the tropical ocean near the Philippine Islands. A storm had taken it northeast, shedding rain, clear to the Japanese coast; it had then moved slowly back before the pressure of the cold wave. By this northern foray it had lost its extreme humidity and warmth, and become temperate rather than tropical. Nevertheless it still remained warmer and more moist than the air which had swept down from Siberia.

The advance of the northern air and corresponding retreat of the southern were related, like all movements in the atmosphere, to conditions existing concurrently over the whole earth. The conditions of this particular day were such that the advance was losing its vigor and becoming slower.