Why do some clusters of Atlantic thunderstorms organize themselves into hurricanes and others do not? Researchers can tell you, in general, the conditions that encourage hurricane formation - such as warm seas and vertically stable winds - but that is not the same thing as knowing which clouds are going to work themselves into a troublesome tropical monster.
Three aircraft are taking to the skies over the tropical Atlantic next month in an ambitious field project designed to directly attack this question - what principal investor Christopher Davis of the National Center for Atmospheric Research in Boulder, Colorado, describes as "one of the long-standing mysteries about hurricanes."
It's been particularly difficult to observe the earliest stages of hurricane development over the years, partly because early development often takes place far from land, and it is difficult to get aircraft on the scene. And the timing is often difficult, because by the time you realize something might be happening, it has already happened, or it may be so far along that it is difficult to figure out why it is happening. The trick really to get aircraft out there early enough that we can see the very beginnings of circulation developing and distinguish situations that lead to a storm versus those that don't.