Thunderstorm out flow from storm core shows up as sheets of wind driven rain spreading from right to left in 1982 photo.

Lowering wall cloud under main thunderstorm updraft. Tornadoes will generally form in and ground the wall cloud.

Tornado near end of life - photographed during "Sound Chase." "Sound Chase" was joint project of NSSL and Mississippi State University. Purpose of project was to record sounds emitted by tornadoes.

Tornado at beginning of life - condensation funnel has not yet reached ground. However, dust cloud at surface indicates tornado touchdown. During "Sound Chase", a joint project of NSSL and Mississippi State University.

Tornado with dust and debris cloud forming at surface. During "Sound Chase", a joint project of NSSL and Mississippi State University.

Tornado with large dust cloud obscuring funnel shape. During "Sound Chase", a joint project of NSSL and Mississippi State University.

"Rope" or decay stage of tornado. During "Sound Chase", a joint project of NSSL and Mississippi State University.

Early stage of tornado formation. Photo #1 of a series of classic photographs of this tornado.

The tornado continues developing. Dust and debris have been carried almost half-way to cloud base. Photo #2 of a series of classic photographs of this tornado.

Tornado in mature stage of development. Photo #3 of a series of classic photographs of this tornado.

Tornado in mature stage of development. Photo #4 of a series of classic photographs of this tornado.

The first tornado captured by the NSSL doppler radar and NSSL chase personnel. The tornado is here in its early stage of formation.

The first tornado captured by the NSSL doppler radar and NSSL chase personnel. The tornado is here in its early stage of formation.

The first tornado captured by the NSSL doppler radar and NSSL chase personnel. The tornado is here in its early stage of formation.

The first tornado captured by the NSSL doppler radar and NSSL chase personnel. The tornado is here in its early stage of formation.

The first tornado captured by the NSSL doppler radar and NSSL chase personnel. The tornado has reached the mature stage of formation.

Tornado in mature stage.

Tornado in mature stage.

Horizontal cloud is ahead of tornado motion while near vertical cloud is behind.

Tornado in mature stage.

Mature stage of large tornado. Clear slot in clouds illuminates funnel.

Roff Tornado.

Roff Tornado.

Alfalfa Tornado.

Project Chase 1984.

Tornado Intercept Project.

Wichita Falls Tornado.

Altus Tornado.

Orienta Tornado.

Arcadia Tornado.

Cheyenne Tornado.

Norman Doppler Radar installation.

Towering Cumulus.

Image from the Binger Doppler Radar.

Image from the Binger Doppler Radar.

Image from the Binger Doppler Radar.

Wall cloud with lightning.

Weather surface forecast office personnel monitoring storm near Oklahoma City.

Air Force Geophysical Laboratory at Sudbury, Massachusetts.

Time evolution of storm on radar.

Time evolution of storm on radar.

A storm chase on June 19, 1980. This picture appeared in National Geographic Magazine.

Norman Doppler radar reflectivity display showing squall line.

Norman Doppler radar display of wind velocities showing dissipating squall line.

Squall line showing distinct gust front.

Squall line as displayed on the Norman Doppler radar.

Hook Echo - often a precursor of tornadic activity.

Flooding associated with downburst.

Microburst (CSU) - extremely dangerous for aircraft

Mayfield Tornado.