During cold periods, though it's evaporating, it falls as snow and gets trapped on the land.

在冷期，虽然也在蒸发，但是以雪的形式降落并困在了陆地上。

It is not clear how many early humans died off during this cold period, the researchers said.

研究人员说，目前还不清楚有多少早期人类在这段寒冷时期死亡。

Their study centered around two cold and dry periods.

他们的研究集中在两个寒冷干燥的时期。

According to Valerie, the coldest period of that little ice age was the Maunder Minimum.

拉蒂夫：根据瓦莱丽的说法，那个小冰河时期最冷的时期是蒙德极小期。

They've analyzed hundreds of such layers, including some from the coldest periods of Earth's history the ice ages.

他们已经分析了数百个这样的地层，包括一些来自地球历史上最寒冷时期的冰河时代。

A team of researchers from Sweden and Spain have pointed out that the vast majority of insects in temperate zones are inactive during cold periods.

来自瑞典和西班牙的一个研究小组指出，温带地区的绝大多数昆虫在寒冷时期是不活跃的。

Researchers found that such cold periods happened at the same time Neanderthals seemed to disappear in different parts of the continent.

研究人员发现，这样的寒冷时期发生在尼安德特人似乎在大陆不同地区消失的同一时间。

This is the dreadful potential of volcanic eruptions, with famines across the other side of the world and even centuries-long cold periods being attributed to them.

这是火山爆发的可怕潜力，世界另一端的饥荒，甚至长达数百年的寒冷时期都归因于它们。

That might account for the biological evidence that life survived this cold period, but it doesn't explain a lot of the geological evidence.

这可能解释了生命在这个寒冷时期幸存下来的生物学证据，但它并没有解释很多地质证据。

The " ice age" is a very cold period of history,approximately 20,000 years ago, when much of the Earth was covered with ice and snow.

“冰河时代” 是一个非常寒冷的历史时期， 大约在 20, 000 年前，当时地球的大部分地区都被冰雪覆盖。

The scientists say Homo erectus, considered the first member of the human family tree to have moved out of Africa was not able to survive a cold period that lasted 4,000 years.

科学家们表示，直立人——被认为是人类族谱中第一个走出非洲的成员——无法在持续4000年的寒冷时期幸存下来。

All economies have hot and cold periods, but the people in charge of the money flow — the Treasury and the Federal Reserve Bank — keep a careful eye on the temperature controls.

所有经济体都有冷热期，但掌管货币流动的人——财政部和联邦储备银行——会密切关注经济的“温度”控制。