Ever wonder how much a cloud weighs? What about a hurricane? A meteorologist（气象学家） has done some estimates and the results might surprise you.

    Let's start with a very simple white puffy cloud—a cumulus cloud(积云). How much does the water in a cumulus cloud weigh? Peggy LeMone, senior scientist at the National Center for Atmospheric Research in Boulder, Colorado, did the numbers. “The water in the little cloud weighs about 550 tons,” she calculates. “Or if you want to convert it to something that might be a little more meaningful...think of elephants.” Assume（假设） an elephant weighs about six tons, she says, that would mean the water inside a typical cumulus cloud would weigh about one hundred elephants.

    The thought of a hundred elephants' worth of water floating in the sky begs another question—what keeps it up there?

    “First of all, the water isn't in elephant-sized particles(微粒); it's in tiny tiny tiny particles,” explains LeMone. And those particles float on the warmer air that's rising below. But still, the concept of so much water floating in the sky was surprising even to a meteorologist like LeMone. “I had no idea how much a cloud would weigh, actually, when I started the calculations（计算）,” she says.

    So how many elephant units of water are inside a big storm cloud—10 times bigger all the way around than the “puffy” cumulus cloud? Again, LeMone did the numbers: About 200,000 elephants.

    Now, come to the calculations for a hurricane about the size of Missouri and the figures get really massive. “What we're doing is weighing the water in one cubic meter theoretically pulled from a cloud and then multiplying by the number of meters in a whole hurricane,” she explains.

    The result? Forty million elephants. That means the water in one hurricane weighs more than all the elephants on the planet. Perhaps even more than all the elephants that have ever lived on the planet.

    Top lists are lecturing people on everything from “100 places to visit” to “100 books to read”. Aren't you just tired of being told what to do with your time?

    Now you have a list to end all lists!

    Take a look at the following two examples from the list of “101 thins not to do”:

    Swim with Dolphins?

    Swimming with dolphins is one of the world's most profitable tourist activities. However, every dolphin will welcome having their busy, tiring day interrupted by tourists screaming pushing around them in the water. Worse yet, when dolphins get too near to the boats loaded tourists, they could get caught up in ropes and killed by propellers(螺旋桨).

    Here's a little secret. Dolphins look like smiling at you, but actually they're just opening mouths.

    Go to see the Mona Lisa?

    There must be something about the mysterious smile. The 6 million people who visit the lady in the Louvre every year can't all be wrong, after all. But they can be quite annoying, standing in front of you, holding up their cameras to prevent you from seeing anything. In fact, it is hard for you to see the painting clearly because you have to stay away from it for security reasons. After queuing for hours, many tourists can remain in front of the painting only for 15 seconds most.

    If the mysterious lady in the picture knew her fate, she wouldn't just be smiling, she'd be laughing.

    So, still long to see the Mona Lisa? If you want to find out more about the list, read 101 Things NOT to Do Before You Die. Visit www. not2dobeforeidie. co. uk and buy the book at a 20% discount.

    Suppose you become a leader in an organization. It's very likely that you'll want to have volunteers to help with the organization's activities. To do so, it should help to understand why people undertake volunteer work and what keeps their interest in the work.

    S Let's begin with the question of why people volunteer. Researchers have identified several factors that motivate people to get involved. For example, people volunteer to express personal values related to unselfishness, to expand their range of experiences, and to strengthen social relationships. If volunteer positions do not meet these needs, people may not wish to participate. To select volunteers, you may need to understand the motivations of the people you wish to attract.

    S People also volunteer because they are required to do so. To increase levels of community service, some schools have launched compulsory volunteer programs. Unfortunately, these programs can shift people's wish of participation from an internal factor (e.g. “I volunteer because it's important to me”) to an external factor (e.g. “I volunteer because I'm required to do so”). When that happens, people become less likely to volunteer in the future. People must be sensitive to this possibility when they make volunteer activities a must.

    S Once people begin to volunteer, what leads them to remain in their positions over time? To answer this question, researchers have conducted follow-up studies in which they track volunteers over time. For instance, one study followed 238 volunteers in Florida over a year. One of the most important factors that influenced their satisfaction as volunteers was the amount of suffering they experienced in their volunteer positions. Although this result may not surprise you, it leads to important practical advice. The researchers note that attention should be given to “training methods that would prepare volunteers for troublesome situations or provide them with strategies for coping with the problem they do experience”.

    S Another study of 302 volunteers at hospitals in Chicago focused on individual differences in the degree to which people view “volunteer” as an important social role. It was assumed that those people for whom the role of volunteer was most part of their personal identity would also be most likely to continue volunteer work. Participants indicated the degree to which the social role mattered by responding to statements such as “Volunteering in Hospital is an important part of who I am.” Consistent with the researchers' expectations, they found a positive correlation(正相关) between the strength of role identity and the length of time people continued to volunteer. These results, once again, lead to concrete advice: “Once an individual begins volunteering, continued efforts might focus on developing a volunteer role identity....Items like T-shirts that allow volunteers to be recognized publicly for their contributions can help strengthen role identity”.

    As soon as a person dies, decomposition(分解) begins. And the first visitors arrive. “Within 5 to 15 minutes of death, flies or other insects begin to colonize the body.” says Rabi Musah, an organic chemist at the University at Albany.

    She says different species turn up at different stages of decomposition. “So because of that, depending upon what entomological(昆虫学的) evidence you find, you can learn something about when the person died in terms of the timing of the death.”

    Flies don't tend to stick around when disturbed by detectives. But they do leave behind eggs. The eggs are hard to tell apart by appearance alone, so specialists raise them until they hatch, a few weeks later—and they get a species ID and, with a little guesswork, a person's time of death.   But Musah has come up with a more time-saving approach: chemical analysis of the eggs. She and her team investigated that method by first harvesting flies with pig-liver traps hidden throughout New York City. They collected the trapped flies and then chemically analyzed their eggs. And it turns out each species of fly egg has a unique chemical fingerprint—enough to tell the eggs apart without raising the eggs to maturity. The study is in the journal Analytical Chemistry.

    Musah and her colleague Jennifer Rosati are now testing the method on a real case. “And once we do that we will be publishing some case studies to illustrate(阐明) that this is a method that can be used, and hopefully eventually it's something that will stand up in court, and something that could speed up detective work—or help deal with a cold case.”

    Art museums are places where people can learn about various cultures. The increasingly popular "design museums" that are opening today, however, perform quite a different role. Unlike most art museums, the design museums show objects that are easily found by the general public. These museums sometimes even place things like fridges and washing machines in the centre of the hall.

    People have argued that design museums are often made use of as advertisements for new industrial technology. But their role is not simply a matter of sales — it's the honouring of excellently invented products. The difference between the window of a department store and the showcase(玻璃陈列柜) in a design museum is that the first tries to sell you something, while the second tells you the success of a sale.

    One advantage of design museums is that they are places where people feel familiar with the exhibits. Unlike the average art museum visitors, design museum visitors seldom feel frightened or puzzled. This is partly because design museums clearly show how and why mass-produced products work and look as they do, and how design has improved the quality of our lives. Art museum exhibits, on the other hand, would most probably fill visitors with a feeling that there is something beyond their understanding.

    In recent years, several new design museums have opened their doors. Each of these museums has tried to satisfy the public's growing interest in the field with new ideas. London's Design Museum, for example, shows a collection of mass-produced objects from Zippo lighters to electric typewriters to a group of Italian fish-tins. The choices open to design museums seem far less strict than those to art museums, and visitors may also sense the humorous part of our society while walking around the exhibits.

    The Adler Planetarium(天文馆) is part of the lake front's "Museum Campus", which along with the Shedd Aquarium(水族馆) and Field Museum, attracts a huge number of visitors every year. The Adler Planetarium is included with the purchase of a Go Chicago Card.

    Address: 1300 South Lake Shore Drive

    Phone: 312-922-STAR(7827)

    Getting to the Adler Planetarium by Public Transportation:

    Either the south-bound CTA bus line #146(Marine-Michigan), or Red Line CTA train south to Roosevelt, then take a Museum Campus trolley (电车) or take the CTA bus #12.

    Driving from Downtown of Chicago:

    Lake Shore Drive (US 41) south to 18th Street. Turn left onto Museum Campus Drive and follow it around Soldier Field. Look for signs that will point you to the visitor parking garage. The Adler Planetarium is just northeast of the parking garage.

Parking at the Adler Planetarium:

    There are several lots(停车场) on the Museum Campus, but most tend to fill up quickly and your best bet is in the main parking garage. Parking for all lots is $ 15 per day.

    Adler Planetarium Hours:

    Daily: 9：30 a. m. -- 4: 30 p. m. The Adler Planetarium is open every day except     Thanksgiving Day and Christmas. Extended Hours: From Memorial Day to Labor Day, the Adler Planetarium is open from 9: 30 a.m.--6: 00 p. m. daily.

    Adler Planetarium Tickets:

    General Admission(exhibits only): Adults, $ 7; Seniors (aged 65+), $ 6；Children(ages 4--11), $5.