According to www.stormchaser.com, there are eight basic categories of storm chasers:
Scientist: Scientists, researchers and support personnel who occasionally (or seasonally) chase storms as part of their research
Hobbyist: A hobbyist is an amateur or "recreational chaser" who pursues severe weather as a hobby. Most of them photograph or video tape severe weather for their archives or sell the footage to help finance their chasing efforts. Some of them have an occupation such as meteorology, education, engineer or college students who study meteorology. Some of the hobbyist category are also retired folks who have the extended time and resources needed in order to chase storms. Many of these hobbyists also serve as "spotters" and will relay critical information to authorities via mobile phones or ham radios. As opposed to "thrill seekers", hobbyists chase storms in a responsible, professional manner. They also comprise the largest group of storm chasers.
Spotters: Spotters are trained localized volunteers such as ham radio operators or public service employees such as law enforcement officers and fire fighters who observe and report threatening weather. Spotters have been called the unsung heroes of chasing, often risking their lives and property to perform their services.
Media/Editorial: These are part time, full time or seasonal chasers and related team members who work for a bonafide news gathering service such as television, news agencies, cable channels and radio stations. This group has been credited with the saving of many lives during the Oklahoma City tornado outbreak in May of 1999. In addition to commercial and editorial applications, the images and footage shot by media chasers are often used for safety, news, scientific and educational purposes.
Thrill Seekers, "Jethros" and "Yahoos": This group of chasers have absolutely no purpose or reason for chasing other than for the thrill. They often compete with each to see who can obtain the most extreme video, while placing themselves and others in danger. They have little or no interest in meteorology and have no respect for the victims of violent weather .They seldom serve as spotters and their conduct reflects poorly on the work of legitimate chasers. The media often glorify this group without revealing the true purpose of their chasing.
Tour Guides: They lead groups of people, for a fee, on actual chases during the severe weather season.
Locals: These are people with little or no chasing experience and who chase or observe storms near their communities. They usually get started on their chase from watching live television weather reports. They pose a hazard by clogging roadways and preventing emergency vehicles and legitimate chasers and spotters from performing their work.
Hurricane Hunters: The Hurricane Hunters are Air Force Reserve (403rd wing) pilots and crew members who fly specially equipped planes into tropical weather and report back to the Tropical Predication Center.