ELI5 Turbulence - how do pilots know it’s coming?

What causes turbulence? How do airplane pilots sometimes know when they about to hit turbulence? Why have heat waves caused airlines to ‘bump’ passengers? How did Van Gough depict turbulence before physicists had even discovered it? ... we explain like I'm five Thank you to the r/explainlikeimfive community whose questions and comments formed the basis of this discussion, especially the following users: miles_by_the_inch, 9country, optionsquare, apleima2, interneerd9 and p_u_c_k_iv To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: [email protected]