1·Surplus snowfall is essential for a glacier to develop.
过剩的降雪是冰川形成的必要条件。
2·Its chances for survival are best if it turns white about the time of the first snowfall.
如果它在第一次降雪时就变成白色，生存几率会是最高的。
3·The cave-making recipe calls for a steady emission of volcanic gas and heat, a heavy annual snowfall at an elevation high enough to keep it from melting during the summer.
洞穴的形成需要火山气体和热量的稳定释放，海拔高到足以防止每年的大量降雪在夏季融化。
4·With further melting, refreezing, and increased weight from newer snowfall above, the snow reaches a granular recrystallized stage intermediate between flakes and ice known as firn.
随着进一步的融化、再结冰，以及上方新的降雪增加的重量，这些雪变成再次结晶阶段的颗粒状中间物，介于小薄片与冰块之间，被称作万年雪。
5·By studying these components, scientists have obtained a detailed archive of many aspects of climate, including air temperatures, snowfall, and concentrations of greenhouses gases in the atmosphere.
通过研究这些成分，科学家们获得了气候的许多方面的详细档案，包括空气温度、降雪和大气中温室气体的浓度。