Spring dance of sprites

Normal lightning shoots out of the cloud base to the ground, sprites leap up from the cloud top.

    Do you know that lightning from a thunderstorm cloud not only hits the ground, but it also shoots upward into the stratosphere, in a phenomenon known as sprites?

    Photographer Paul M Smith does - and late last month he set out to capture it after a series of unusually severe spring storms developed in the southeast region of the United States.

    As residents on April 22 took shelter from golf-ball-sized hail and dangerous tornadoes, sprites were emerging high above the thunderstorms.

    "There were tornado warnings and very large hail throughout the night," Smith, of Edmond in Oklahoma, told spaceweather.com. "I photographed the sprites through a clearing around midnight."

    Sprites are another form of electrical discharge from large storm clouds. While normal lightning reaches from the cloud base to the ground, sprites leap up from the cloud top, dispersing electrical charge into the stratosphere. 

    In both cases, it is the thunderstorm cloud that creates the necessary voltage, through internal friction, to produce these discharges.

    Sprites can reach all the way to the edge of space, 90km (56 miles) or more above the Earth's surface. Spring thunderstorms often produce the year's first big sprites, and the sightings continue until late summer.

    According to spaceweather.com, this could turn into one of the best sprite seasons on record because of the solar minimum. The sun is currently showing the lowest rate of sunspots in at least 100 years, indicative of a weak magnetic field. As the sun's magnetic field weakens, more cosmic rays from deep space are reaching Earth, rather than being attracted to the sun.

    There is scientific speculation that more cosmic rays lead to more lightning, including sprites. This season may provide some more evidence. Even if this influence cannot be proven, the climate regularly provides the necessary storm clouds over the Plains States in the US and many other places around the world.

    SOURCE: Al Jazeera and news agencies