The Aeronauts
I watched the 2019 film entitled The Aeronauts. This movie is based on a true story, and it is about a scientist named James Glaisher. He was one of the first people to really study weather. The movie focused on a hot air balloon flight that Glaisher embarked on in 1862. The directors added another character named Amelia Wren. This flight became the highest anyone had ever been; above 29,000 ft. Glaisher hoped that by completing the flight, he would better understand the weather and then be able to predict it. In the movie, it indicated that no one else had much interest in trying to predict the weather yet, making James Glaisher one of the pioneers of meteorology. In the movie, throughout the hot air balloon flight, the aeronaut takes readings of the temperature and other weather conditions. They encounter clouds, a thunderstorm, endure extreme temperatures, and experience lack of oxygen. In this movie, there were two times when the weather was truly extreme. This was when they flew through the thunderstorm and when they got high enough that they could barely move due to the cold temperatures and lack of oxygen. The weather was not used so much to move the story forward, but more to add dramatic effect. The thunderstorm seemed to be added into the historical account, but the extremely low temperature and pressure were present to depict the story accurately. In this essay I will assess the accuracy of the movie The Aeronauts with regard to the temperature and characteristics of the atmosphere. This will include a discussion of temperature lapse rate, air stability, and the associated weather formations. I will largely draw upon my knowledge of weather as a pilot as well as various reliable sources of weather, science, and history to assess the accuracy of the film.
The atmosphere is made up of different layers. The lowest layer is the troposphere. After the troposphere comes the stratosphere, the mesosphere, the thermosphere, and the exosphere (UCAR). Once you get to the tropopause, the boundary between the troposphere and the stratosphere, the temperature lapse rate changes and then it starts getting warmer with an increase in altitude. The height of the tropopause varies with latitude, and is around 10 km above the surface, or around 33,000 feet above sea level in the midlatitudes. In the troposphere, the temperature decreases at a relatively standard rate (UCAR). The Pilot’s Handbook of Aeronautical Knowledge says that the standard (average) temperature lapse rate is -3.5°F per every one thousand foot increase in altitude (FAA). Air is described as unstable when the temperature lapse rate is not stable. This can occur because warmer air tends to rise while cooler air tends to sink. Thunderstorms thrive on instability. Thunderstorms need three things to form: instability, sufficient moisture, and lifting action. They are filled with updrafts and downdrafts that can sometimes even destroy small aircraft. The fact that hot air rises and cold air sinks is also the principle that hot air balloons use to fly through the air. By filling the balloon with warmer air, the hot air balloon rises above the colder air surrounding it.
“The Aeronauts” shows the ascension of a hot air balloon where the main character periodically mentions various weather observations he has made at their altitude. In order to assess the accuracy of this film, I will compare the mentioned weather readings from the film to what readings were collected historically as well as with what I would predict would occur based on my knowledge of weather. The chart below shows this comparison. All temperatures are in Fahrenheit. The calculations were made based on assuming standard temperature lapse rate and assuming the movie had the correct temperature at 5,500 ft.
| Temp/Dew Point | Data in movie | By Calculation | Data in actual flight |
| Surface | —/— | 83°/— | 59°/48° |
| ≈5,500 | 64°/— | 64°/— | 41°/38° |
| ≈10,000 | —/— | 48°/— | 32°/26° |
| ≈26,000 | 5°/— | -8°/— | -5°/-36° |
| Highest Altitude | —/— | —/— | -12°/— |
This data shows that the temperature given in the movie at 26,000 ft is 18°F off of what a standard temperature lapse rate would have indicated and 10°F off of what actually was recorded. The data shows that the temperatures given in the movie were very far off from what actually was recorded by James Glaisher. In Glaisher’s journal, he wrote, “a very delicate minimum thermometer was found to read minus 12 degrees, and that reading would indicate an elevation exceeding 36,000 ft” (Brearly). Since the balloon was bordering the end of the troposphere, the last indication of -12° could have been an indication after the tropopause was crossed and the temperature began to increase with height. Since Glaisher did not know about the tropopause, he must have assumed that the temperature just continued to decrease and thus, estimated a height of around 37,000 ft. This is confirmed by one commenter who wrote “Glaisher’s attempt to calculate the balloon’s maximum altitude must surely be flawed. Both men would have been dead in seconds at 36,000 ft. Their known height of 29,000 ft. was still a world record” (Brearly). The movie directors decided to keep the incorrect estimate of 37,000 ft in the movie, which makes sense, but in my opinion, they should have just used the actual temperatures that Glaisher recorded rather than just throw out numbers for the temperature.
When it comes to temperature, the movie was not very accurate, but the movie did correctly depict the updrafts and downdrafts that would be present in a thunderstorm. This scene can be viewed here: https://www.youtube.com/watch?v=VBJiJqPOn4M . However, one issue is that in the movie, they experienced no turbulence below or when nearing the thunderstorm, only while in the cloud. This is inaccurate because turbulence from a thunderstorm would be felt below a thunderstorm. James Glaisher wrote, “at the height of one mile the temperature was 41 degrees and the dew-point 38 degrees. Shortly afterwards clouds were entered of about 1,100 ft. in thickness” (Brearly). The movie did show the clouds being entered right after their 5,500 ft indication, which is very close to how long a mile is. Pilots will sometimes use an equation to find the base of clouds. This is done by finding the difference between the temperature and the dew point and then dividing it by 4.4 if the temperatures are in Fahrenheit. Then you multiply it by 1000 to get the cloud base in ft above ground level. Out of curiosity, I applied this equation to the temperature and dew point that was recorded at the surface in real life by Glaisher. That gave me that the cloud base should be at around 2,500 ft, which is about 3,000 ft lower than was actually observed.
The last thing I wanted to observe was the accuracy of the time of useful consciousness in a hypoxic state. In the Pilot’s Handbook of Aeronautical Knowledge, they have a chart that indicates that at 30,000 ft above sea level, they would only be conscious for about 1-2 minutes. Which, in both real life and in the movie, was good enough to get the top of the hot air balloon open to release the hot air and begin a descent. This part of the film seemed very accurate because they got the top of the balloon open and then immediately passed out, similar to the account from James Glaisher’s journal.
In conclusion, the film “The Aeronauts” is somewhat accurate for both the depiction of unstable air and lack of oxygen, but it was far off when it came to giving observations of the temperature. This movie was quite enjoyable to watch and assess. It told the story of James Glaisher in a fun and exciting way, though some historical accuracies were compromised.
Bibliography
UCAR. (n.d.). Atmosphere. Retrieved November 06, 2020, from https://scied.ucar.edu/learning-zone/atmosphere
Brearley, T. (n.d.). James Glaisher. Retrieved November 06, 2020, from http://www.thosemagnificentmen.co.uk/balloons/glaisher.html
Pilot’s Handbook of Aeronautical Knowledge. (2016). Washington, D.C.: U.S. Department of Transportation, Federal Aviation Administration, Flight Standards Service.
Harper, Tom, director. The Aeronauts, Amazon Prime Video, 2019, www.youtube.com/watch?v=VBJiJqPOn4M.