Q: What is a typhoon?
A: It's basically the same thing as a hurricane. Both are tropical cyclones – rapidly rotating storms that typically form in warm tropical waters and feature low pressure centers, high winds and lots of rain.
If the storm originates in the Atlantic or Northeast Pacific, we call them "hurricanes." If they form in the Northwest Pacific, they're called "typhoons." Elsewhere, they're called "cyclones." But they're all the same thing. Big tropical storms.
Q: What makes a "super typhoon"?
A: That's the term that weather agencies use for particularly severe tropical cyclones, although the precise definition can vary from country to country.
The U.S. Navy's Joint Typhoon Warning Center designates a typhoon "super" when the wind speed reaches 130 knots, or 150 miles per hour. That's roughly equivalent to a Category 5 hurricane.
Q: So how intense is super typhoon Haiyan?
A: Very. Before hitting land Friday, the storm's winds reached speeds of 195 mph, with gusts rising above 230 mph. Those are some of the highest wind speeds ever recorded.
Q: Is Haiyan the strongest tropical storm ever?
A: Possibly. The most precise way to measure a tropical cyclone's intensity is to fly an aircraft into the eye of the storm and drop instruments to measure wind speed and air pressure. Those aircraft aren't available in this case. However, satellite estimates by the Joint Typhoon Warning Center suggest that Haiyan may end up being one of the strongest storms of the satellite era. Indeed, before making landfall, the storm appeared to be approaching the top end of the intensity scale – it was about as intense a storm as is physically possible.
At its peak, Haiyan appeared to be more intense than Hurricane Katrina, with winds of 165 mph, albeit covering a smaller area.
Jeff Masters of Weather Underground argued that when Haiyan hit the Philippines, it was likely the most powerful tropical storm to make landfall on record.
Q: Why are super typhoons so deadly?
A: Same reason hurricanes are deadly. High winds, lots of rain, flooding. In the Philippines, heavy rains can often cause the most death and destruction in the mountainous regions, since they can trigger flash floods and mudslides.
Q: Have there been an unusual number of typhoons this year?
A: It's difficult to say. So far, the 2013 Pacific Typhoon season has seen 30 storms, 13 typhoons and roughly five "super typhoons." But the season isn't necessarily over.
Those 30 storms makes this the most active Pacific Typhoon season since 1994. On the other hand, those five "super typhoons" aren't necessarily unusual.
Q: Could global warming make tropical cyclones more destructive?
A: Yes – but there are caveats. It's still not entirely clear what effect climate change will have on the tropical cyclones themselves. The latest IPCC report said it was "likely" that tropical cyclones around the world would get stronger as the world warms, with faster winds and heavier rainfall. But the overall number of hurricanes would likely "either decrease or remain essentially unchanged."
There is, however, an important asterisk here: Climate scientists are much more confident that sea levels will keep rising as the oceans warm and glaciers and ice caps melt. And that will escalate the risk of storm surges when tropical cyclones do hit, particularly in low-lying areas.