Turbulence occurs when there are disturbances in the movement of the air that cannot be seen. This irregular movement of air varies in intensity and often occurs unexpectedly, no matter which of the four types of turbulence occurs, whether it is mechanical, aerodynamic or wake turbulence, shear or thermal turbulence.
Identifying Thermal Turbulence
Thermal turbulence is the result of differential ground heating, according to Principal Air Ltd. Different types of surfaces are heated by the sun at different rates. Thermal turbulence is similar to mechanical turbulence in that it is more severe when planes are flying at lower altitudes. Thermal turbulence occurs most often during the summer and is more likely to occur in areas that are hot, such as in areas closer to deserts. The hottest hours of the day also increase the likelihood that a plane will experience thermal turbulence.
Captain Meryl Getline, a United Airlines Captain and award-winning author detailing the experiences of her career answered questions for her 2005 USA Today column, “Bumpy But Not Dangerous,” where one person who frequently flew out west from the Detroit area asked why turbulence always seemed to be greater when flying from Las Vegas or Arizona back to Detroit than when flying from Detroit to the destinations in the western part of the country. Captain Getline explained that thermal turbulence was the cause of the greater turbulence when flying from Las Vegas or Arizona locations. She explained that as things heat up during the day, heat rises, but not evenly. Mix in the uneven rise of afternoon heat with a little desert winds and voila! You have instant thermal turbulence.
Integrated Publishing’s “Types of Turbulence” suggests that light thermal turbulence will occur on days where there are light winds and “an unstable lapse rate in the lower few thousand feet; light turbulence is likely to occur under areas of developing cumulus clouds, noting that thermals “rarely exceed 10,000 feet AGL without forming clouds and being classified as convective turbulence.” Moderate thermal turbulence can be expected where there is extreme heat and low humidity or “exceptionally large dust devils.” Due to the fact that thermal turbulence is more likely to occur and with the most severity at the hottest hours of the day, particularly during summer months, as well as in areas such as those western locations as described by Captain Getline, it is understandable that Alexander Burton, CFI, of Principal Air, Chilliwack Airport of Chilliwack, B.C., says that thermal turbulence “can result in some interesting experiences during landing and takeoff when we are operating aircraft in close proximity to the ground and at low airspeed.”
Effective Means of Protecting Yourself During Thermal Turbulence
The most effective means of protecting yourself and loved ones when the aircraft you are flying on experiences thermal turbulence is to first follow basic guidelines given when any aircraft is experiencing any of the other types of turbulence; follow directions that you are given by the flight crew and do so immediately. The Federal Aviation Administration (FAA) revealed in the article,” Turbulence: Staying Safe,” that it is imperative for all passengers to follow FAA requirements that passengers stay seated with seatbelts fastened until the aircraft has climbed after takeoff, during landing and taxi, as well as whenever the seatbelt sign is illuminated on your plane. The FAA reminds us that in-flight turbulence is the primary cause of injuries to passengers and flight attendants. Two of three fatalities caused during turbulence occurred when passengers did not have their seat belts secured, even though the seat belt sign was illuminated at the time.
Since most turbulence-related injuries occur when planes are flying at 30,000 feet or above, thermal turbulence may be less likely to cause injuries to passengers and flight attendants. But thermal turbulence is still a regular occurrence, just like the other types of turbulence and it is imperative to take measures to protect yourself and loved ones from the possibility of injury from thermal turbulence. By becoming knowledgeable of what thermal turbulence is, when and where it is most likely to occur and by following the FAA rules as well as instructions of members of the flight crew every time you fly, you are more likely to have a safe and fun flight experience.