One weekend in May 2015, over 48 centimeters of rain fell in Houston, Texas, USA. Soon the city was covered with water. The rising water rushed into the cars on the roads. There were 16 deaths that weekend.

      Changing Weather

      The weather is changing. Over the last few years, heavy rains have caused floods (洪灾) in Brazil, Pakistan, and Thailand. Droughts (干旱) have struck Russia and Australia. Heat waves have killed thousands in Europe. There are more different kinds of terrible wild weather all over the world. In 2011 alone, the bad weather caused the world to lose 150 billion dollars.　

      Warmer and Wetter

      As more wild weather events happen, a worried world is beginning to ask questions like: What is going on with the weather? And why? Many also want to know: Is this natural, or are we to blame (责怪)?

      The answer seems to be: a little of both. Wild weather is natural.   ▲   This global (全球的) warming makes heat waves more likely to happen. The higher temperatures also cause more water to enter the air. This causes much more rain. Some scientists also believe global warming makes some storms stronger.

      This means we're likely to see more wild weather. “But we don't have to just stand there and take it,” says Scientist Michael Oppenheimer. He and other scientists say we need to stop the Earth from getting warmer. We also need to be prepared, to do things that will help save lives.

    Have you ever wondered why birds sing? Maybe you thought that they were just happy. After all, you probably sing or whistle when you are happy.

    Some scientists believe that birds do sing some of the time just because they are happy. However, they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.

    Do you know what a 'territory' is? A territory is an area that an animal, usually the male, claims as its own. Only he and his family are welcome there. No other families of the same species are welcome. Your yard and house are your territory where only your family and friends are welcome. If a stranger should enter your territory and threaten you, you might shout. Probably this would be enough to frighten him away.

    If so, you have actually scared the stranger away without having to fight him. A bird does the same thing. But he expects an outsider almost any time, especially at nesting（筑巢）season. So he is screaming all the time, whether he can see an outsider or not. This screaming is what we call a bird's song, and it is usually enough to keep an outsider away.

    Birds sing loudest in the spring when they are trying to attract a mate and warn others not to enter the territory of theirs.

    You can see that birds have a language of their own. Most of it has to do with attracting mates and setting up territories.

    On July 20, 1969, Neil Armstrong became the first person to walk on the moon. The space suit Armstrong wore on his lunar mission has come to symbolize courage and human achievement. In 1971, the Smithsonian's National Air and Space Museum(NASM), in Washington, D.C., acquired (获得) Armstrong's suit. It stood proudly on display for visitors to admire, until there were changes in the suit's appearance. "Over time, the suit started to show signs of deterioration," Lisa Young said. Young is an objects conservator (文物修复员) at NASM. It is her job to preserve(维护)historical and cultural objects.

    "Plastics are tricky to conserve," Young says. They tend to degrade (降解)over time. Neoprene is one type of plastic in Armstrong's suit. The material can turn brittle and break into tiny pieces. This would ruin the space suit. NASM, seeking ways to preserve this historical treasure, removed it from display in 2006.

    What causes plastic to degrade in the first place? "Many things," Odile Madden says. Madden is a scientist in California. She explains that sunlight, water, humidity, and dust can cause plastics to degrade. "Some plastics will break down no matter what we do," Madden says.

    Yet history can still be saved. Scientists have found that storing plastics in cooler temperatures, with lower humidity levels, can slow degradation. Young says Armstrong's suit is currently in storage at a temperature of 63°F and a lower relative humidity of 30%. These conditions will be maintained when Armstrong's suit returns to a museum display case in time for the 50^th anniversary of the moon landing.

    Plastic degradation affects art, too. Artist Claes Oldenburg created False Food Selection in 1966.It consists of plastic food displayed in a wooden box. The plastic food used to look real. Now, some of it has flattened and yellowed. Georgina Rayner is a conservation scientist at Harvard Art Museums, in Cambridge. She says the artwork's wooden box produces an acidic (酸的) gas that eats away at the plastic. This speeds up the degradation process. But Rayner is motivated to conserve this artwork and others like it. "Plastics are a part of our history," she says. "It's important to preserve them so that future generations can understand the journey we've taken."

    Are you angry by the noise of your alarm clock every morning? Still feel sleepy after getting up? Now, you can say goodbye to that annoying alarm clock, you needn't hear its unpleasant noise every morning.

    The Glow pillow (发光枕)can wake you up with soft LED lights. The lights produce the brightness over 40 minutes just like the sunrise.

The pillow is taking the place of the traditional alarm clock. It was designed (设计)by Eosin McNally and Ian Walton to be against the pressures of a"24 hour "lifestyle.

    The pillow uses a kind of LED material below the surface. It wakes the user up with light. The material can also show the time on the pillow's surface, and it is perfect for those who sleep with their heads completely buried(埋)face down into the pillow. 40 minutes before the pre-set(预设)alarm time, the pillow begins to glow and gently brings the user out of sleep. The natural waking process helps to set "body clock" and makes people build a healthy sleep-and-wake habit slowly.