揭秘龍卷風是如何形成的
Mother nature is known for her irony. And last week’s tornadoes that ripped through the American heartland are a case in point.
Just days after the VORTEX2 scientists, part of largest study of tornadoes in history, packed up their instruments after only snagging one single twister—the Midwest got hit with more than 75 tornadoes, across seven states.
The National Oceanic and Atmospheric Association reports 873 twisters this year, while last year had nearly double, at 1691. Not great news for scientists wanting to study twisters this summer. But there’s always next year.
VORTEX2 received nearly $12 million in funding from the National Science Foundation, NOAA and various universities and organizations, to go out in the field for two seasons.
Nearly 100 researchers literally surrounded tornadic storms with mobile radar and wind, humidity, pressure and temperature instruments, in an attempt to answer a deceptively simple question: how to accurately predict when a tornado will form.
“The predictability is still an unknown,” that’s Don Burgess, retired chief of the Warning Research and Development Division NOAA, and now at the Cooperative Institute for Mesoscale Meteorological Studies at the University of Oklahoma. “Whether the processes are so complicated and such small scales dominate—whether we can really forecast them in the future an hour or more is something about which right now we don’t know.”
The seemingly unlimited changes in variables like wind direction, temperature, or moisture, and having such few sample cases (they only have one sample from VORTEX2), make it a near impossible challenge to precisely nail down why one storm produces a tornado and another very similar storm does not.
“But, the way that I look at it is that this research project, and I think the same analogy is true in a lot of research, it’s like an onion. And that onion has lots of layers. In VORTEX1 we peeled back some of those layers. Since then we’ve learned some more, we have better technology we maybe peeled back another layer or two. Now we’re looking at that onion and I know in VORTEX2 we’re going to peel back more layers but do we get to the core or not—my guess, based on being around this for forty years—is we’re not going to get to the core. We’re going to push back the horizons, we’re going to better and we’re going to get more understanding, we’re going to get more predictability, we’re going to get better applications for warnings to the public. But are we going to solve it soon? No.”
大自然以她的反常而著稱。上周肆虐美國中部地區的龍卷風就是一例。
就在“旋渦2”(旋渦2是歷史上最大的龍卷風研究項目的一部分)的科學家們僅僅抓住了一次龍卷風的研究機會，收拾起他們的儀器后幾天——美國中西部的7個州遭受到了超過75次龍卷風的襲擊。
今年美國國家海洋與大氣總署(The National Oceanic and Atmospheric Association，簡稱NOCC)報道了873例龍卷風，去年的數字幾乎是今年的兩倍，達到了1691例。對于今年夏天想研究龍卷風的科學家們來說，今年的龍卷風的這個數目不是個很好的消息。但是明年總會是還有的。
“旋渦2”接受來自美國國家科學基金(National Science Foundation)、美國國家海洋與大氣總署(NOAA)以及各種大學和機構的基金資助，資助數額接近1千2百萬美元，這些基金用于資助科學家們到野外研究兩個季節的龍卷風。
接近有100名研究者攜帶可移動雷達以及測量風、濕度、壓力、溫度的儀器圍繞在可以形成龍卷風風暴的四周進行觀測，以期回答一個看似極為簡單的問題：怎樣準確地預測龍卷風什么時候形成。
Don Burgess曾經是NOAA的預警研究和發展處主任(Warning Research and Development Division)，他目前退休后到了奧克拉荷馬大學(University of Oklahoma)的中尺度氣象研究合作研究所(Cooperative Institute for Mesoscale Meteorological Studies)工作。他說：“龍卷風是否可以預測目前仍然是個未知數，是否這個過程如此的復雜，以致于這些小尺度的變量占支配地位---未來我們是否能真正地提前一個小時預報——對于這些我們目前仍不得而知。”
形成龍卷風的變量似乎多的不計其數，比如風向、溫度，或者濕度，加上樣本非常有限(從旋渦2中科學家們僅僅只獲得了一個樣本)，這就使得要精確地知道為什么某個風暴形成了龍卷風，而另外一個非常類似的風暴并沒有形成幾乎是不可能的挑戰。
“但是，我看這個研究項目的方式是，它就像在剝洋蔥，而且我認為這個類比也適合其它許多的研究項目，如果我們有更好的技術，我們會再剝掉一兩層。目前我們正在關注這個洋蔥，我知道在`旋渦2'中，我們會剝去更多的洋蔥層，但是我們是否剝到了核心呢---根據我40年的研究經歷，我猜測，我們還不會剝到核心。我們會有更寬廣的視野、我們會做得更好而且我們會了解得更多、我們會預測得更好、我們會為公眾做更好的預警。但是我們能很快解決這個問題嗎?不會那么快。”
小留學生 parachute kids
留學生這個詞我們并不陌生，而且都知道是指那些成年以后到別國深造學習的學生。不過，好像現在有越來越多的家長愿意讓孩子從小就到國外接受教育，這些被送到國外的小孩子就被稱為parachute kids。
Parachute kids are children sent to a new country to live alone or with a caregiver while their parents remain in their home country, also called parachute children.
Parachute kids(降落傘兒童)，也叫做parachute children，指那些被送到另一個國家獨自生活的孩子。他們的生活起居有人照顧，但是父母仍然留在本國。
這種現象早些年在香港和臺灣地區比較常見。這些小孩的父母經常奔波與港臺和孩子所在國家，就像“空中飛人”一樣，所以這一類父母被人戲稱為astronaut parents。由此，被“空中飛人”父母空投到某國生活的孩子被叫做parachute kids也就不奇怪了。