揭秘龙卷风是如何形成的
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称。上周肆虐美国中部地区的龙卷风就是一例。
就在“旋涡2”(旋涡2是历史上最大的龙卷风研究项目的一部分)的科学家们仅仅抓住了一次龙卷风的研究机会，收拾起他们的仪器后几天——美国中西部的7个州遭受到了超过75次龙卷风的袭击。
今年美国国家海洋与大气总署(The National Oceanic and Atmospheric Association，简称NOCC)报道了873例龙卷风，去年的数字几乎是今年的两倍，达到了1691例。对于今年夏天想研究龙卷风的科学家们来说，今年的龙卷风的这个数目不是个很好的消息。但是明年总会是还有的。
“旋涡2”接受来自美国国家科学基金(National Science Foundation)、美国国家海洋与大气总署(NOAA)以及各种大学和机构的基金资助，资助数额接近1千2百万美元，这些基金用于资助科学家们到野外研究两个季节的龙卷风。
接近有100名研究者携带可移动雷达以及测量风、湿度、压力、温度的仪器围绕在可以形成龙卷风风暴的四周进行观测，以期回答一个看似极为简单的问题：怎样准确地预测龙卷风什么时候形成。
Don Burgess曾经是NOAA的预警研究和发展处主任(Warning Research and Development Division)，他目前退休后到了奥克拉荷马大学(University of Oklahoma)的中尺度气象研究合作研究所(Cooperative Institute for Mesoscale Meteorological Studies)工作。他说：“龙卷风是否可以预测目前仍然是个未知数，是否这个过程如此的复杂，以致于这些小尺度的变量占支配地位---未来我们是否能真正地提前一个小时预报——对于这些我们目前仍不得而知。”
形成龙卷风的变量似乎多的不计其数，比如风向、温度，或者湿度，加上样本非常有限(从旋涡2中科学家们仅仅只获得了一个样本)，这就使得要精确地知道为什么某个风暴形成了龙卷风，而另外一个非常类似的风暴并没有形成几乎是不可能的挑战。
“但是，我看这个研究项目的方式是，它就像在剥洋葱，而且我认为这个类比也适合其它许多的研究项目，如果我们有更好的技术，我们会再剥掉一两层。目前我们正在关注这个洋葱，我知道在`旋涡2'中，我们会剥去更多的洋葱层，但是我们是否剥到了核心呢---根据我40年的研究经历，我猜测，我们还不会剥到核心。我们会有更宽广的视野、我们会做得更好而且我们会了解得更多、我们会预测得更好、我们会为公众做更好的预警。但是我们能很快解决这个问题吗?不会那么快。”
小留学生 parachute kids
留学生这个词我们并不陌生，而且都知道是指那些成年以后到别国深造学习的学生。不过，好像现在有越来越多的家长愿意让孩子从小就到国外接受教育，这些被送到国外的小孩子就被称为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(降落伞儿童)，也叫做parachute children，指那些被送到另一个国家独自生活的孩子。他们的生活起居有人照顾，但是父母仍然留在本国。
这种现象早些年在香港和台湾地区比较常见。这些小孩的父母经常奔波与港台和孩子所在国家，就像“空中飞人”一样，所以这一类父母被人戏称为astronaut parents。由此，被“空中飞人”父母空投到某国生活的孩子被叫做parachute kids也就不奇怪了。