Here's a photo I took through my windscreen last night - the a/c is highlighted because it's a bit indistinct - but this is Air NZ flight ANZ548 flying Christchurch - Auckland at about 07.45pm local time shot from Lower Hutt - facing west - so it is flying over the South Taranaki Bight to the west of Wellington.
The point here is that this aircraft has left a persistent contrail ("top one" to the left), and is currently leaving a non-persistent one - it is a multi-tasking chemtrailer!!
The 2nd persistent contrail on the left (the "bottom" one) was probably left by ANZ674 which flew by 30 minutes earlier from Dunedin to Auckland.
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