contrails

[perkin]

just been watching assorted traffic overflying dutch airspace and was wondering what affects the length of an aircrafts contrail? some aircraft have very long contrails, some hardly any at all. can anyone explain what factors determine how quickly the contrail disperses? thanks in advance... :)

[BOAC]

http://cimss.ssec.wisc.edu/wxwise/class/contrail.html

[perkin]

many thanks for that BOAC, if I'd thought enough about it I would've remembered back to my student days and worked it out for myself! My assumption is that as each aircraft is likely to be on a different flight level then the relative humidity of each flight level is slightly different resulting in contrails of different magnitude....I assume aircraft/engine type must have some bearing on this too? Would a small aircraft produce a smaller contrail when passing through the same air mass than a significantly larger one?