Hole Punch Clouds, Canal Clouds, and Fallstreak Holes are all names for an interesting cloud phenomenon where a hole forms in a thin layer of cloud, usually with a streak of cloud falling from the middle of the hole. They are relatively rare (I see them a few times a year, and I watch the sky a lot) but also very photogenic, so a Google image search shows up lots of nice examples, see above. Hole punch clouds form when a layer of supercooled liquid water cloud is disturbed by something (usually a plane) and this triggers freezing of the droplets, which further disturbs the layer, causing more freezing. The resultant ice crystals are composed of the water from several drops, so are heavier than the surrounding cloud and fall out. This is the "fallstreak" you see in the middle, it's essentially snow. Generally hole punch clouds are formed by an aircraft passing through the cloud layer, and the angle at which it passes through determines the shape of the hole, the shallower the angle, the longer the hole. When the hole is very long (if a plane happens to be cruising at the same altitude as the cloud, or is just climbing or descending very slowly) then this creates a long hole, sometimes referred to as a "canal cloud". These can be quite long: I was recently asked on Twitter if these hole punch clouds showed up in old books on clouds Source: https://twitter.com/FleshnChrome/status/812474808852049920 And of course they do, and I found an example: Source: https://twitter.com/MickWest/status/813773001862692864 But I thought it might be interesting to look at the history of these holes. They have only been occurring with some frequency in the same timeframe as contrails, since they are largely triggered by airplanes. However they could be triggered by other thing, depending on how ideal the conditions are. Precipitation from higher clouds might do it, even the passage of a bird, or something from below, like a forest fire. So along the lines of similar threads on contrails, or halos and sun dogs, what is the history of observations of hole punch clouds? The example I posted on Twitter was from 1972, the book Clouds of the World, by Richard Scorer, page 105. "glaciation" here essentially means freezing, and "nucleated" refers to the fact that the ice crystals act both as condensation nuclei for water vapor still in the air, and as freezing nuclei for any water droplets they come into contact with. (The above photo is by H. H. Samuelson, and also appears in Scorer's Environmental Aerodynamics, 1978, Page 425) The 4.3.5 referred to is this interesting example, seemingly of four linked holes. Also predating 1972. A much earlier example comes from the book Cloud Study, A Pictorial Guide. by Scorer, et al, published in 1957 And from the same 1957 book on page 79 there's an example of a canal cloud: So 1957 is a far back as I can go with books in my collection. They must have occurred before, at least as far back as the 1920s or 1930s although they would have been far more rare. It's also possible they were observed before powered aviation, although I'm not aware of any reports. A more comprehensive survey was carried out by Peter V. Hobbes in his 1985 article Hole in Clouds: A Case of Scientific Amensia/ Hobbes says: I have the 1943 edition of Clouds, however I can't see what Hobbes might be referring to. However, some of the other Hobbes references are worth following up on. Update: Here's the 1948 photo by Poulter, PDF attached. Spoiler: Hobbes References Braham, R. R. Jr and P. Spyers-Duran, 1967: Survival of cirrus crystals in clear air. J. Appl. Meteor., 6, 1053-1061. Brunt, D., 1946: Patterns in ice and cloud. Weather, 1, 184-185. Cave, C. J. P., 1926: Clouds, Cambridge University Press. Hallett, J. and S. C. Mossop, 1974: Production of secondary ice particles during the riming process. Nature, 249, 26-28. Hobbs, P. V., 1984: Production of ice crystals. Weatherwise, 37, 119. and N. T. Funk, 1984: Cloud and precipitation studies with a millimeter-wave radar: A pictorial overview. Weather, 39, 334-339. Johnson, H. M. and R. L. Holle, 1969: Observations and comments on two simultaneous cloud holes over Miami. Bull. Amer. Met. Soc., 50, 157-161. Ludlam, F. H., 1956: Fall-streak holes. Weather, I I, 89-90. Mossop, S. C., 1978: The influence ofdrop size distribution on the production of secondary ice particles during graupel growth. Quart. J. Roy. Meteor. SOG., 104, 323-330. and J. Hallett, 1974: Ice crystal concentration in cumulus clouds: influence of the drop spectrum. Science, Poulter, R. M., 1948: Man-made cirrus? Weather, 3, 232-233. Radke, L. F. and P. H. Herzegh, 1977: Natural seeding with accompanying release of precipitation. Beit. Phys. Atmosph., 50, 448-495. Rangno, A. L. and P. V. Hobbs, 1983: Production of ice particles in clouds due to aircraft penetrations. J. Clim. Appl. Meteor., 22, 214-232. , 1984: Further observations of the production of ice particles in clouds by aircraft. J. Clim. Appt. Meteor., 23, Schumacher, C., 1940: Beobachtungen an einer Altokumulusdecke. 2. angew. Met., 57, 214-220. Scorer, R., 1964: Fallstreak holes. Weafher, 19, 90-91. , 1972: Cloudr ofthe World, David and Charles Pub. Co., 176 pp. Simon, A., 1966: Dissipation d’un altocumulus sur le passage d’un avion a reaction. J. Rech. Atmos., 2, 36-38. Stuart, J. M., 1954: Distrails. Meteor. Mag., 84, 58-59. Trecarten, L. A., 1961: Fall-streak holes. Weather, 13, 404-406. Vonnegut, B., 1948: Production of ice crystals by the adiabatic expansion of gas. J. Appl. Phys., 19, 959. , 1985: Nucleation of ice crystals in supercooled clouds caused by passage of an airplane. J. Clim. Appl. Meteor. (in press).