Robert Henson

The Rough Guide to Climate Change: Climate Chanqe and El Niño

cycle is ENSO (El Niño/Southern Oscillation), whose two modes are known as El Niño and La Niña. ENSO is based in the tropical Pacific Ocean, which spans a third of the globe from Ecuador to Indonesia. Trade winds blow more or less continuously across this huge area from east to west, pushing warm water towards Indonesia, where the resulting warm water helps lead to persistent showers and thunderstorms. The cold, upwelled water off Ecuador and Peru, meanwhile, stabilizes the air there and produces the region’s legendary aridity (Peru’s capital, Lima, gets about the same amount of rain each year as Cairo). About every two to seven years, the trade winds weaken or reverse, the surface layer of warm water deepens and expands into the eastern tropical Pacific, and an El Niño sets in, typically lasting one or two years. The flip side, La Niña, occurs when trade winds are stronger than average, pushing cooler-than-usual water westward into the central tropical Pacific. About half of the time, neither El Niño or La Niña is in progress and the Pacific is neutral. El Niño increases the odds of drought across Indonesia, Australia, India, southeast Africa, and northern South America. It tends to produce mild, b y R o b er t H en so n excerpt

Avalanche!: When the Snow Comes Tumbling Down

Abstract As people flock to North Americas mountains, more and more are coming face-to-face with the terror of avalanches.

Hurricanes in Disguise

Youngsters in western Massachusetts enjoyed a treat on Halloween Eve 1991: crisp and pleasant weather. Nature was playing all of its tricks on people along the New England coast. A storm of surprising intensity the day before had brought waves of 25 feet crashing onto the shore and swells of more than 100 feet at sea. Thousands of coastal homes were seriously damaged, and Atlantic City recorded its second highest tide of record. Damage costs soared into the hundreds of millions, approaching the levels inflicted by Hurricane Bob only weeks earlier.

Model Behavior: How to Get a Jump on the Weathercaster with the Detailed Forecasts on the Web

always resemble what you see on your local weathercast. This 48hour forecast from the US. Navy‘s NOGAPS model (as linked from the University of Michigan weather page) shows the height of the 500-millibar pressure surface (solid contours) in tens of meters, as well as maxima and minima of vorticity (circulation) in red and blue, respectively. Low heights correspond to low-pressure centers aloft, as shown in Arizona and New Mexico and far off the East Coast. ou’re watching your local late-night weathercast, and the drama is enough to Y rival ER (for a weather fan, anyway). A storm system is taking shape over the Pacific and heading toward the United States. It could cause huge late-season snows across the Rockies and, eventually, severe weather across the Plains. But, the weathercaster stresses, “the computer models don’t agree on where this storm is headed.” One model wants to lift it northeast, another digs it southeast. That would be the difference between sunshine and snowplows for big stretches of the West. The weathercaster finally shrugs and says, “We’ll see what tomorrow mornings models have to say.”