Low-Flying Aircraft (apologies to JGB)

I have transcribed below a letter published in this week's Hastings and St Leonard's Observer, a not untypical example of the kind of material frequently submitted. I have omitted the name and address of the sender - it could of course be an Ortonesque prank (not guilty). I have never witnessed this alleged phenomenon myself, although coastguard and military planes and helicopters sometimes fly low along the coast - we also get a lot of sea mist at certain times of the year (term times?):

(headline is 'Cloudbusting above [sic] the skies of Hastings?')

I would like to ask the councillors of Hastings to explain what is going on in the skies over the town.

I live facing a local school and college and I have noticed that every term time, the skies over the area have planes constantly flying at low altitudes and leaving behind a trail which spreads out during the course of the day and forms grey clouds which can be seen dropping slowly into grey mist over the areas. I have researched normal contrails that are a natural occurrence when planes are flying at high altitudes, this contrail disperses very quickly, but these low flying aeroplanes criss cross across the sky leaving grids which is [sic] predominantly over the schools and college.

So my question is, why is this happening? And while I am on the subject, who is responsible for this and what is in the cloud that it doesn't disperse as normal?

And why only in term time?

If they have no answers then who does?

I have heard of weather modification and I would think that people should know exactly what's going on and if there are any dangers especially when its [sic] seen to happen over local schools, has anyone else noticed this phenonema [sic]?