A Cloud Rolls In Later, as an adult, I flew halfway around the world to see an even more unusual cloud. I waited for days in a dusty town in Australia, hoping to see it. Day aſt er day, I looked up and saw nothing. Finally, aſt er 11 days, a slight breeze began


to blow. I could feel a change coming. Far out at sea, two winds collided, sending a giant wave of air toward the land. If you could have seen it, the wave would have looked like a giant ocean wave rolling across the sea. T is wave of air can rise 3 km high, and stretch 1,000 km long. As it rolled over the sea, it picked up moist


air. Vapor rode up the front of the wave, cooling and condensing into a giant cloud shaped like a tube. It rolled over flat land, with nothing to stop it or slow it. As I watched, this cloud rolled toward me


at 50 kph. As it rolled over my head, it blocked the moon and stars, and then it rolled away. T is rare cloud is called the Morning Glory.


Bubbling Clouds Knowing how air, land, and water interact led me to the right place and right time to see a Morning Glory cloud. Other clouds are more mysterious. We don’t know exactly how they form, so it can take luck to see them. I got lucky driving through a storm in


France one day. Above me, the storm clouds started to change. T e clouds sagged in spots, forming spheres that dangled like bubbles. Soon, these bubbles filled the entire sky. I felt like I’d driven into an alien world. T ese clouds don’t follow the same rules


as other clouds. T ey’re made mostly of ice crystals even though they don’t form at a high altitude. And instead of forming as vapor rises and cools, they form when cool dry air high up in the atmosphere falls and freezes moist air closer to the ground. Scientists aren’t sure yet why this happens.


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This cloud is just like the Morning Glory cloud I saw.


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