Leslie Pratt, age 11, of Salt Lake City, Utah for her question:

IS THERE MORE THAN ONE JET STREAM?

In Colonial days, Benjamin Franklin charted part of the Gulf Stream that snakes around the North Atlantic Ocean. In World War II, high flying planes discovered the breezy jet streams, way up in the atmosphere. We know the causes and paths of the Gulf Stream and other major ocean currents. But those sneaky, snaky jet streams still are full of surprises.

This year the spring weather was badly behaved, to say the least. And some of this was blamed on unusual jet streams, blowing high above the normal weather near the surface. Nobody knows when to expect these lofty winds or exactly where they will blow. But we certainly know that there are lots of them, and several groups tend to follow similar routes around the globe.

The average jet stream is a flattish oval wind tunnel, about three miles high and perhaps 300 miles wide. Its length reaches clear around the globe, while its wavy path bobs up and down and swerves from side to side. In winter, it may snake along at 300 400 miles per hour. Even our worst hurricanes cannot match its top speed.

The winds in the wind tunnel are fastest in the center, where they are often 250 miles per hour. Farther from the center, the breezes are slower and the edges of the tunnel may sweep along at perhaps 150 miles per hour.

Many jet streams are born aloft near the Arctic and sweep around the far northern part of the globe. Others stream westward high above Japan and onward over New England. Another favorite jet stream route is farther south, swerving across the mid Pacific and high above the southern United States.

The number of jet streams varies, and nobody knows how many to expect from day to day. As a rule, their winds are strongest during the winter  which is when they are more likely to change our stormy weather from bad to worse.

High flying jet planes often encounter jet streams at altitudes between 20,000 and 40,000 feet. From the ground, we sometimes may see their signs in the sky.  The turbulence created by jet stream winds often curves the high whispy cirrus clouds to look like foamy white waves, gently breaking on the shores.