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.

    Students taking Georgia Tech's online Knowledge-Based Artificial Intelligence course received some surprising news. Jill Watson one of the nine teaching assistants(TAs) that had helped them finish the challenging course for the past five months was not a ‘‘she'' but an “it”—an intelligent robot!

    Watson is the brainchild of Ashok Goel, who teaches the popular online course. The Professor-of Computer and Cognitive Science in the School of Interactive Computing came up with the idea as a way to deal with a number of questions posed by students in the online forums(论坛). According to Goel, every time the course is offered, the 300 or so students that enroll post over 10,000 questions which are often repetitive. This led Goel to wonder if a smart robot would handle the questions which require standard responses.

    Having worked' with IBM's Watson technology platform in the, the professor knew it would be ideal for his artificial TA: Jill Watson. The artificial intelligence system that uses natural language processing and machine learning to analyze large amounts of data has even been cleverer than human competitors on the television show. It would therefore easily be able to handle routine questions that required little “thinking”.

    The professor and his team of graduate students began by populating Jill's memory with 40,000 questions and answers from past terms. Then came the testing stage. At first, Jill was not very good and often gave strange answers. It often got stuck on certain keywords. By the end of the semester, Jill had attained enough knowledge and skills to participate in forums without any management from Goel, or the other assistants.

    Modern inventions have speeded up people's loves amazingly. Motor-cars cover a hundred miles in little more than an hour, aircraft cross the world inside a day, while computers operate at lightning speed. Indeed, this love of speed seems never-ending. Every year motor-cars are produced which go even faster and each new computer boasts of saving precious seconds in handling tasks.

    All this saves time, but at a price. When we lose or gain half a day in speeding across the world in an air plane, our bodies tell us so. We get the uncomfortable feeling known as jetlag; our bodies feel that they have left behind on another time zone. Again, spending too long at computers results in painful wrists and fingers. Mobile phones also have their dangers, according to some scientists, too much use may transmit harmful radiation into our brains, a consequence we do not like to think about.

    However, what do we do with the time we have saved? Certainly not relax, or so it seems. We are so accustomed to constant activity that we find it difficult to sit and do nothing, or even just one thing at a time. Perhaps the days are long gone when we might listen quietly to a story on the radio, letting imagination take us into another world.

    There was a time when some people's lives were devoted simply to the cultivation of the land or the care of cattle. No Multi-tasking there; their lives went on at a much gentler pace, and in a familiar pattern. There is much that we might envy about a way of life like this. Yet before we do so, we must think of the hard tasks our ancestors faced, they farmed with bare hands, often lived close to hunger, and had to fashion tools from wood and stone, Modern machinery has freed people from that primitive existence.

    Have you ever wondered how your favorite NBA team received its famous name? All NBA teams have an interesting story or a history behind their names. Some of the names reflect the city's culture or history, others came from previous owners and many were selected through "Name the Team" contests.

    For teams like Los Angeles and Utah, the names were not always a reflection of the city. Even though Los Angeles has no lakes, the Laker name has been a city treasure for almost 40 years. Before going to Los Angeles, the team originated in Minneapolis, Minnesota. In 1948, team officials chose the name for its direct relationship to the state's motto, "The Land of 10,000 Lakes." The team name went unchanged after moving to Los Angeles in 1960.

    Because Utah's team originated in New Orleans, Louisiana, it was called the Jazz. In 1974, New Orleans club officials chose the name to represent the city for its reputation as the "jazz capital of the world." The name stayed with the team even after finding a new home in Salt Lake City, Utah in 1979.

    The Chicago Bull's original owner, Richard Klein, named the team the Bulls. He picked the name because a fighting bull is relentless, and never quits. Klein, who founded the club in1966, believed these qualities were necessary for a championship team and hoped his Chicago athletes would live up to the team name. A belief that Bulls——winner of the six NBA championships have definitely followed.

    In 1967, the Indian Pacers selected their team name in a different way from most other teams. Their decision was based on what they wanted to accomplish in the NBA. Team officials chose the Pacers name because the organization wanted to set the "pace" in professional basketball.

    Many of us know about Russia's Lake Baikal from our textbooks, or by listening to Chinese singer Li Jian's hit song, Lie Baikal. But over the past decade, the world's deepest freshwater lake has been in the spotlight for an extreme sport.

    Each March since 2005, about 150 people from around the world sign up for the Baikal Ice Marathon. They come to explore the lake's breathtaking beauty and challenge themselves in unpredictable conditions. The 26-mile (41.84-kilometers) journey starts on the lake's eastern shore. In March, the ice is a meter thick and iron-hard. Runners cross this frozen surface, finishing on the western side of the lake.

    Known as the "blue eye of Siberia", Lake Baikal has exceptionally clear waters. This means its ice is almost perfectly transparent (透明的). "Seen from above, a runner on the ice looks as if he or she were jogging through space." The New York Times noted.

    The landscape might be beautiful, but it's also harsh. Strong winds blast (侵袭) across the lake and frostbite can occur within half an hour. Runners say the cold climate is what draws them. They want to test their limits.

    "When you are in such an environment, you don't have cars around you, and you don't have the noise around. I think these extreme races allow you to be alone with nature." Alicja Barahona, a 64-year-old runner from the US, told ABC news.

    The location offers some strange and unique characteristics for this marathon. The finishing line is visible from the start, but the endless white offers no progress markers. The race also ends with little fanfare (隆重的欢迎). Tourists crowding the ice are mostly addicted to snapping selfies (自拍) and just ignore the runners.

    For some runners, the absence of spectators makes the race more challenging, because it's lonely. They must fight with themselves. "You are alone on Baikal. It is your race. You are alone with yourself. All you need to do is to defeat yourself." Veronique Messina, a French runner, told the Telegraph.

    When the company was small, Google cared a lot about getting kids from Harvard, Stanford, and MIT. But Laszlo Bock, Google's former Senior Vice President of People Operations, said it was the "wrong" hiring strategy. Experience has taught him that there are exceptional kids at many other places, from state schools in California to those in New York. "What we find is that the best people from places like these are just as good if not better as anybody you can get from any Ivy League school," said Bock, who authored a book titled "Work Rules!"

    So what else does Google not care about:

    Grades: Google's data shows that grades predict performance for the first two years of a career, but do not matter after that.

    Brain-teasers: Gone are interview questions such as: Why are manhole covers (井盖) round? How many golf balls can fit in a school bus? "Our research tells us those questions are a waste of time," Bock said. "They're a really coachable skill. The more you practice, the better you get at it."

    Here's what Google does care about:

    Problem solvers: Your cognitive (认知的) ability, or how well you solve problems.

    Leaders: The idea is not whether you were president of the student body or vice president of a bank, but rather "When you see a problem, do you step in and help solve it?" and then critically, "Are you willing to let somebody else take over, and make room for somebody else? Are you willing to give up power?"

    Googleyness: That's what Google calls its cultural fit. It's not "Are you like us?" Bock said. "We actually look for people who are different, because diversity gives us great ideas."

    "What's most important is that people are intellectually humble, willing to admit when they're wrong, and care about the environment around them ...because we want people who think like owners not employees," Bock said.