“Let's have a journey. Why not fly out and meet me, Dad?” I say one day.

    My father had just retired after 27 years as a manager for IBM. His job filled his day, his thoughts, and his life. While he woke up and took a warm shower, I screamed under a freezing waterfall in Peru. While he tied a tie and put on the same Swiss watch, I rowed a boat across Lake of the Ozarks.

    My father sees me drifting aimlessly, nothing to show for my 33 years but a passport full of funny stamps. He wants me to settle down, but now I want him to find an adventure.

    He agrees to travel with me through the national parks. We meet four weeks later in Rapid City.

    “What's our first stop？” asks my father.

    “What time is it？”

    “Still don't have a watch？”

    Less than an hour away is Mount Rushmore. As he stares up at the four Presidents carved in granite(花岗岩), his mouth and eyes open slowly, like those of a little boy.

    “Unbelievable,” he says. “How was this done？”

    A film in the information center shows sculptor Gutzon Borglum devoted 14 years to the sculpture and then left the final touches to his son.

    We stare up and I ask myself, “Would I ever devote my life to anything？”

    No directions, no goals. I always used to hear those words in my father's voice. Now I hear them in my own.

    The next day we're at Yellowstone National Park, where we have a picnic.

    “Did you ever travel with your dad？” I ask.

    “Only once,” he says. “I never spoke much with my father. We loved each other — but never said it. Whatever he could give me, he gave.”

    That last sentence — it's probably the same thing I'd say about my father. And what I'd want my child to say about me.

    In Glacier National Park, my father says, “I've never seen water so blue.” I have, in several places of the world. I can keep traveling, I realize — and maybe a regular job won't be as dull as I feared.

    Weeks after our trip, I call my father.

    “The photos from the trip are wonderful,” he says. “We've got to take another trip like that sometime.”

I tell him I've decided to settle down, and I'm wearing a watch.

    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.

    Animal lovers have long suspected that playing with pups was good for the soul, and now science has confirmed it – for students in particular.

    The results of a new study done by researchers at the University of British Columbia concluded that the college students who spent time at drop-in dog therapy sessions experienced an increase in feelings of wellness and a reduction in overall stress. The study, as reported by Science Daily, indicates that playing with pups is not only popular with the students, it's also beneficial to their health. This finding was seen across gender（性别）.

    The study, which published on March 12 in the journal Stress and Health, involved 246 students who were surveyed before and after they dropped by dog therapy sessions. The young participants were given free access to pet, hug with and talk to seven to 12 therapy dogs. Additionally, they filled out questionnaires right before and right after hanging with the dogs, as well as 10 hours later.

    According to researchers, these young adults reported a notable increase in happiness, a significant reduction in stress and a flood of energy right after their sessions with the pups. Although the reported feelings of happiness and satisfaction weren't long-lasting, researchers say other effects have clear, positive advantages.

    “These sessions clearly provide benefits for students in the short-term, so we think universities should try to schedule them during particularly stressful times, such as around exam periods,” Assistant Professor of Psychology at UBC and the study's senior author, Frances Chen told Science Daily. “Even having therapy dogs around while students are working on their out-of-class assignments could be helpful.”

    An earthquake is one of the most common natural disasters. It may cause great damage. So it is wise to learn some simple safety tips to protect yourself or your family members.

    Fragile items, like those made of glass should usually be placed on a lower surface, near the ground instead of placing them on cupboards higher up. Never place them near your bed, sofas and other furniture where you would be sitting or lying down. When there is a strong movement, these pieces will fall on the floor directly and not on you.

    There is a strong chance of short circuit (短路) and fire breakouts during an earthquake. Make sure you turn off electrical connections and gas immediately when an earthquake happens.

    During an earthquake, lie beneath an object that is not easily damaged. Do not go near objects that could directly fall on you. Never use the elevator to go down. Stay inside until the shaking stops and it is safe to go outside. Research has shown that most injuries happen when people inside buildings try to go out. Use the staircases at all times.

    If you are outdoors, do not take shelter under a tree, streetlights, electric poles or tall buildings. If you are driving, stop your car and stay in a safe place. Do not park your car under a tree or any tall object.

    If trapped in debris (瓦砾堆), cover your mouth with a handkerchief or clothing. Tap on a pipe or wall so rescuers can find you. Use a whistle (哨子) if you have one. Never shout for help. Shouting can cause you to breathe in dangerous amounts of dust. Do not light a match because you may burn yourself. Do not move about or kick up dust.

    Last summer, bird-watchers confirmed the discovery of a new species of bird in Cambodia was not an event of particular biological significance, but it was striking for one reason in part. This species of bird was discovered not in an unspoiled rain forest but within the limits Cambodia's capital, Phnom Penh – a city the size of Philadelphia.

What the researchers found was surprising in cities. The medium-sized city in the state about 110 species of birds, over 95 percent of which would have been growing there urbanization. Ecologically speaking, cities are different, concrete buildings. Rather, each unique bio-profile – a kind of ecological fingerprint – that is against the idea of an environment dead zone.

    Of course, it's also true that in the world of birds and plants, as in human society, there is such a thing as worldwide—the city-inhabitants who feel equally at home in San Francisco, Milan and Beijing. Four birds occur in more than 80 percent of the cities studied, and 11 plants occurred in more than 90 percent of the cities. On the plant side, those are seemingly spread by European settlement. In the air, it's the usual suspects: the rock pigeon and many other birds. “They have become completely adapted to urban life,”Katti says. “That's not much of surprise. But they don't actually dominate as much as we think they do.” Those species—occurring in the cities across the globe—represent only a small part of a city's natural varieties.

    Not all cities are equal protectors of native animals and plants, though. One of the biggest predictors for a city's biodiversity is its urban design. Territory as varied as backyards and street trees can lay important roles in greening a city. In fact, the amount of green space is a stronger predictor of the density of biodiversity than a city's size. A metropolis with a sizable network of parks can contain more species per square mile than a much smaller city.

    In a world where architecture, food, language, fashion and commerce are increasingly globalized, a city's native animals and plants can be a kind of identity. There may be neighborhoods in London and Paris that resemble Singapore or Hong Kong. Cities are becoming similar, but their natural environments stand completely apart.

    When 12 girls from San Fernando high school in California received a grant (助学金) to develop an invention to solve a real-world problem, they decided to create a solar-powered shelter. Now for over a year, the girls have been working after school and over the winter and spring breaks to complete their project. "They have this amazing drive that I've never seen before," said Violet Mardirosian, a math teacher at San Fernando High. "I thought at the beginning that maybe some of them would give up, saying 'I didn't expect this much work,' but they don't. They're just working hard and they're not giving up."

    Living in a low-income community (社区), the girls have seen the problem of homelessness first-hand, which is why they chose that population to create a product for. Many of them are also from immigrant families and hope the solar-powered shelter might help refugees (难民). Seventeen-year-old Maggie Mejia said that while she had no engineering experience, the girls figured out as a team how to create the prototype (雏形), using how-to videos and books that taught them how to code. But the most important lesson she's learned over the course of the project isn't technical. "I've learned a lot about helping others, helping the community and showing a better world to other people," she said.

    The girls have been invited to MIT to show their invention. Mardirosian says all the participating students have expressed interest in going into STEM (science, technology, engineering, mathematics) fields and that students from lower grades are already expressing interest in being involved next year. She says, "Many of them didn't think about engineering before. They thought maybe they're not made out to be an engineer. But working together, now they realize they're all needed in this field. Everyone has found their importance in this picture."