Most people understand the concept of mechanical turbulence during air travel, but they may not understand what thermal turbulence is. In fact, most people have probably never even heard of the term at all. So, what is thermal turbulence? Thermal turbulence feels like a general bumping and rocking of the airliner which can be felt by passengers inside of the plane. It is never a severe shaking, but a rather mild one in comparison to mechanical turbulence.
Thermal turbulence is generated from the solar heat that comes off of the ground coming into contact with cooler air that is higher up from the ground. Obviously, this is an occurrence that is much more likely in the summer months than it is at other times of the year. Air passengers are most likely to experience thermal turbulence in the early afternoon when the sun is shining the hottest onto the ground. They are also more likely to experience it in the Midwest or the high desert regions where the temperatures are generally higher, than they are in other parts of the country. In the high desert, there are also different wind currents generated from the hills and mountains which will lead to more thermal turbulence.
Thermal turbulence occurs most often when an aircraft is flying at lower altitudes. This is most common during take-offs and landings or when flying in the pattern of the airport waiting to approach the runway. The increase in thermal turbulence is because the jet is closer to the ground, where the solar heat is being generated and causing heat waves.
Thermal turbulence can feel a bit scary even though it is fairly mild turbulence, especially to passengers who are inexperienced fliers or fearful of flying in general, but it is not dangerous. Professional airline pilots are well-trained and are quite adept at dealing with what is, to them, very light turbulence. Thermal turbulence is nothing new to them, as it is a rather common experience that they deal with during flights. Even though it may seem like something is wrong when your flight is going through thermal turbulence, this is not the case at all. There is nothing to worry about when it occurs, so sit back and enjoy the ride, understanding what is happening and that you are going to be just fine.