Putting aside for the moment the concept that 21ºC is ‘hot’, she does seem to have a point. If it’s too hot for contrails, then surely the trails spotted must be chemtrails.
But how hot was it at flight altitude? It does, after all, get a lot colder as you go higher. Luckily, it seems there are a few websites that collate and display the upper air readings made around NZ each day. I assume the source is the MetService upper air data, but their display of the data is unreadable, and learning how to interpret Met VUWs tehphigrams is something I’m going to put aside for another day. The best place I could find that displays the data in nice human-readable format was (of all places) the University of Wyoming’s Department of Atmospheric Sciences, where you can plug in a station code to get the corresponding data back.
Here’s the two readings from Paraparaumu (closest station to Wellington) for that day (one in the morning, one in the evening). As you can see on the 21Z reading, when it’s nearly 21 degrees at ground level, it’s actually somewhere between -35ºC and -50ºC up at flight altitudes. Cold enough for contrails to form?
I looked around the NZ chemtrails sites to find out the best way to interpret these results, and found that Clare Swinney recommends the use of the Appleman Chart — a simple enough chart that allows you to determine the likelihood of contrails forming given various altitude/temperature/pressure/humidity combinations). Again, an excellent tool for determining what might and might not be a chemtrail — if the conditions aren’t right, a contrail can’t form, therefore what’s left is mostly likely a chemtrail! So, plotting those numbers from a typical cruising altitude of 35000ft (250hPA, -46.9ºC, 27% rel/humidity), we get…