H


uge hurricanes spin. Floodwaters rise.


Droughts scorch the ground. Heat waves and deep freezes grip the planet. Extreme weather is battering nearly every


corner of Earth. It’s breaking records and causing natural disasters. It’s also raising a lot of questions. What’s up with the weather? Is something


pushing it to extremes? Or are these disasters part of normal weather patterns? To answer these questions, meteorologists


are studying weather disasters for clues. T ey want to see if weather patterns are changing. It will take time to find answers. Weather


patterns change over a long period of time. One disaster doesn’t prove there’s been a change, but many disasters might.


Water Cycle Meteorologists start with what they know about weather patterns. T ey look at the interaction of the sun, ocean, and wind. First, the sun’s energy warms Earth and


evaporates water. T e water changes from a liquid into a vapor that rises into the air. When the water vapor rises high enough,


winds push it. T e biggest winds blow in patterns. Jet streams, for example, blow west to east high in the atmosphere. Others big winds blow toward the Equator from east to west. All of these winds carry the vapor long distances. Eventually, air cools the vapor. T e vapor


condenses and turns back into a liquid. T en it falls back to the ground as precipitation, such as rain. T is process is called the water cycle. Precipitation usually follows these patterns.


So meteorologists oſt en can predict the weather for a specific place and time. Now, though, it’s getting harder for them to get their predictions right. Surprising things are happening.


18 NATIONAL GEOGRAPHIC EXTREME EXPLORER


Ocean water evaporates, forming a vapor that rises into the air.


Rising Water One recent spring day, rain began to fall in a city in the southern United States (U.S.). It didn’t seem like a big deal. T e city gets about 14 cm of rain each May. Meteorologists had used weather patterns to predict the storm. Soon, though, puddles turned into lakes


and rivers overflowed. Flooding water gushed over a highway, trapping cars and trucks. Families climbed on the roofs of their houses to escape floodwaters. By the time the storm ended a few days


later, it had dumped 43 cm of rain. No one had predicted this much rain. T is was no ordinary storm. It caused a flood that happens once in 1,000 years in this part of the world. T is disaster wasn’t unique. Soon aſt er,


heavy rain fell in Pakistan. By the time it stopped, water covered a fiſt h of the country. A few months later, rain drenched part


of Australia. Floods trapped people in their homes. Roads disappeared. Crocodiles, which normally stay near rivers, now swam down flooded city streets!


Water Ways Follow the water cycle.


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