Earth and Sky:Fire Cycle 火灾规律

Fire Cycle 火灾规律

The El Nino phenomenon of 1997-98 unleashed¹ torrential rain in some parts of the world, while creating abnormally dry conditions in others. And it sparked record numbers of wildfires. Learn more about climate and wildfire -- today on Earth and Sky.

JB: This is Earth and Sky. We spoke² with fire expert Steve Pyne of Arizona State University in Tempe -- about fire and climate, the long term pattern of weather.

Steve Pyne: Climate is of course one of the fundamental shapers of fire. The ideal climate for fire is a pattern of wetting and drying. That is to say, what you want to know is how frequent, and how intense are the wet and dry spells. So, many places go through a wetting and drying cycle every year, which is to say they have an annual fire cycle. So, it has to be wet enough to grow stuff, and then dry enough to prepare it to burn.

DB: For example, desert fires are more frequent after unusually wet seasons -- such as during an El Nino year -- because more plants spring up.

Steve Pyne: The biggest fire seasons are those that are dry after a period of wet runs. So you've had several years to build up everything, now it suddenly turns dry and you're ready to burn. Or places where there is a very violent fluctuation³, places that are normally very wet, suddenly and unexpectedly turn dry. Places that are very dry suddenly become flush with water, and all kinds of ephemerals and such sprout⁴ up.

DB: So fire and climate are linked. Special thanks today to the Bureau of Land Management and to the National Fish and Wildlife Foundation -- supporting the conservation of native fish, wildlife, plants and their habitats. I'm Deborah Byrd for Earth and Sky.

1 unleashed   

v.把（感情、力量等）释放出来，发泄( unleash的过去式和过去分词 )

参考例句：

• The government's proposals unleashed a storm of protest in the press. 政府的提案引发了新闻界的抗议浪潮。
• The full force of his rage was unleashed against me. 他把所有的怒气都发泄在我身上。 来自《简明英汉词典》

2 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

3 fluctuation   

n.(物价的)波动，涨落；周期性变动；脉动

参考例句：

• The erratic fluctuation of market prices are in consequence of unstable economy.经济波动致使市场物价忽起忽落。
• Early and adequate drainage is essential if fluctuation occurs.有波动感时，应及早地充分引流。

4 sprout   

n.芽，萌芽；vt.使发芽，摘去芽；vi.长芽，抽条

参考例句：

• When do deer first sprout horns?鹿在多大的时候开始长出角？
• It takes about a week for the seeds to sprout.这些种子大约要一周后才会发芽。