Global warming could bring us more Sandys
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The Sahara reaches its hottest in July and August, sending massive, spiraling columns of super-heated air from the ground into the atmosphere, according to hurricanescience.org, a website developed by the University of Rhode Island Graduate School of Oceanography to promote a better understanding of hurricanes. The columns of hot air, known as dirt devils, drift from northwest Africa into the Atlantic, becoming what meteorologists call “African easterly jets,” cyclones that are blown across the ocean by the moderate trade winds that once carried sailing ships from port to port.
As an easterly jet makes its way across the Atlantic, it kicks up warm sea spray high into the troposphere, the lower level of the atmosphere, where weather happens. As it reaches the troposphere’s outer boundary, it meets cold air and condenses to form thunderclouds. The jet will continue to suck up sea spray from the ocean like a giant straw until it meets cold water from below, which doesn’t evaporate and is too heavy to be carried into the atmosphere.
The more warm water that a jet can draw from the ocean, the better chance that it will morph from a mere tropical depression into a tropical storm and eventually a full-blown hurricane. The size and strength of a hurricane depend largely on the storm’s ability to draw water and energy from the ocean into the atmosphere.
Which brings me to climate change, a.k.a. global warming, the slow heating of the Earth over time. For decades, climate scientists have argued that the carbon dioxide we send into the atmosphere from factories, power plants and vehicles is raising the planet’s mean temperature, causing glacial melting, sea-level rise — and an increase in the temperature of our oceans, meaning that there’s more warm water to fuel hurricanes.
We won’t necessarily see a greater number of hurricanes in a warmer world, scientists say. We’ve had 19 named storms for each of the past three years, most of which, thankfully, never reached land. But we could see more superstorms like Katrina and Sandy in the future because of global warming.