揭秘龍卷風(fēng)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(guó)中部地區(qū)的龍卷風(fēng)就是一例。
就在“旋渦2”(旋渦2是歷史上最大的龍卷風(fēng)研究項(xiàng)目的一部分)的科學(xué)家們僅僅抓住了一次龍卷風(fēng)的研究機(jī)會(huì)，收拾起他們的儀器后幾天——美國(guó)中西部的7個(gè)州遭受到了超過(guò)75次龍卷風(fēng)的襲擊。
今年美國(guó)國(guó)家海洋與大氣總署(The National Oceanic and Atmospheric Association，簡(jiǎn)稱NOCC)報(bào)道了873例龍卷風(fēng)，去年的數(shù)字幾乎是今年的兩倍，達(dá)到了1691例。對(duì)于今年夏天想研究龍卷風(fēng)的科學(xué)家們來(lái)說(shuō)，今年的龍卷風(fēng)的這個(gè)數(shù)目不是個(gè)很好的消息。但是明年總會(huì)是還有的。
“旋渦2”接受來(lái)自美國(guó)國(guó)家科學(xué)基金(National Science Foundation)、美國(guó)國(guó)家海洋與大氣總署(NOAA)以及各種大學(xué)和機(jī)構(gòu)的基金資助，資助數(shù)額接近1千2百萬(wàn)美元，這些基金用于資助科學(xué)家們到野外研究?jī)蓚�(gè)季節(jié)的龍卷風(fēng)。
接近有100名研究者攜帶可移動(dòng)雷達(dá)以及測(cè)量風(fēng)、濕度、壓力、溫度的儀器圍繞在可以形成龍卷風(fēng)風(fēng)暴的四周進(jìn)行觀測(cè)，以期回答一個(gè)看似極為簡(jiǎn)單的問(wèn)題：怎樣準(zhǔn)確地預(yù)測(cè)龍卷風(fēng)什么時(shí)候形成。
Don Burgess曾經(jīng)是NOAA的預(yù)警研究和發(fā)展處主任(Warning Research and Development Division)，他目前退休后到了奧克拉荷馬大學(xué)(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(shuō)：“龍卷風(fēng)是否可以預(yù)測(cè)目前仍然是個(gè)未知數(shù)，是否這個(gè)過(guò)程如此的復(fù)雜，以致于這些小尺度的變量占支配地位---未來(lái)我們是否能真正地提前一個(gè)小時(shí)預(yù)報(bào)——對(duì)于這些我們目前仍不得而知。”
形成龍卷風(fēng)的變量似乎多的不計(jì)其數(shù)，比如風(fēng)向、溫度，或者濕度，加上樣本非常有限(從旋渦2中科學(xué)家們僅僅只獲得了一個(gè)樣本)，這就使得要精確地知道為什么某個(gè)風(fēng)暴形成了龍卷風(fēng)，而另外一個(gè)非常類似的風(fēng)暴并沒(méi)有形成幾乎是不可能的挑戰(zhàn)。
“但是，我看這個(gè)研究項(xiàng)目的方式是，它就像在剝洋蔥，而且我認(rèn)為這個(gè)類比也適合其它許多的研究項(xiàng)目，如果我們有更好的技術(shù)，我們會(huì)再剝掉一兩層。目前我們正在關(guān)注這個(gè)洋蔥，我知道在`旋渦2'中，我們會(huì)剝?nèi)ジ嗟难笫[層，但是我們是否剝到了核心呢---根據(jù)我40年的研究經(jīng)歷，我猜測(cè)，我們還不會(huì)剝到核心。我們會(huì)有更寬廣的視野、我們會(huì)做得更好而且我們會(huì)了解得更多、我們會(huì)預(yù)測(cè)得更好、我們會(huì)為公眾做更好的預(yù)警。但是我們能很快解決這個(gè)問(wèn)題嗎?不會(huì)那么快。”
小留學(xué)生 parachute kids
留學(xué)生這個(gè)詞我們并不陌生，而且都知道是指那些成年以后到別國(guó)深造學(xué)習(xí)的學(xué)生。不過(guò)，好像現(xiàn)在有越來(lái)越多的家長(zhǎng)愿意讓孩子從小就到國(guó)外接受教育，這些被送到國(guó)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(gè)國(guó)家獨(dú)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(guó)。
這種現(xiàn)象早些年在香港和臺(tái)灣地區(qū)比較常見(jiàn)。這些小孩的父母經(jīng)常奔波與港臺(tái)和孩子所在國(guó)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(guó)生活的孩子被叫做parachute kids也就不奇怪了。