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北冰洋的冬季从11月起直到次年4月，长达6个月。而夏季仅7、8两个月。北极的冬天是漫长、寒冷而黑暗的，从每年的11月23日开始，有近半年时间是几乎看不见太阳的日子。到了4月份，才慢慢暖和起来，冰雪逐渐消融。而北极地区的夏季却出现了剧烈的冰融现象，科学家对此研究表明，这与热浪期有着一些联系。
In the summer of 2012， the U.S. was baked. From the end of June to the end of July， temperature records were set across the middle of the country. And the cause may have been the record-setting meltdown of Arctic sea ice.
The loss of sea ice leads to a weakening of winds high in the atmosphere. The reduced temperature difference between the Arctic and lower latitudes diminishes the jet stream as well. It also moves the jet stream north， letting hot air sit longer.
Such a lessening of the jet stream may have been responsible for Hurricane Sandy turning ashore and wreaking havoc in New York City and New Jersey. And the phenomenon extends beyond North America. Weak jet streams have prolonged heat waves in Russia as well as parked downpours over Europe.
One thing’s for sure： increasing concentrations of greenhouse gases in the atmosphere will continue to warm the Arctic and melt ice and snow. And that could mean much hotter summers across the northern hemisphere.
Vocabularies
In the summer of 2012， the U.S. was baked. From the end of June to the end of July， temperature records were set across the middle of the country. And the cause may have been the record-setting meltdown of Arctic sea ice.
The loss of sea ice leads to a weakening of winds high in the atmosphere. The reduced temperature difference between the Arctic and lower latitudes diminishes the jet stream as well. It also moves the jet stream north， letting hot air sit longer.
Such a lessening of the jet stream may have been responsible for Hurricane Sandy turning ashore and wreaking havoc in New York City and New Jersey. And the phenomenon extends beyond North America. Weak jet streams have prolonged heat waves in Russia as well as parked downpours over Europe.
One thing’s for sure： increasing concentrations of greenhouse gases in the atmosphere will continue to warm the Arctic and melt ice and snow. And that could mean much hotter summers across the northern hemisphere.
Vocabularies
