He uses aggressive and emotive phrases about it: wind turbines are “ugly monstrosities” which will “destroy” Scotland.
Quite why the Chinese manufacturers whom Trump holds responsible are laughing at the First Minister isn’t clear, but presumably Trump wants to suggest that they hold him in as much contempt as he does.
Warming to his theme, Trump accuses Mr Salmond of leaving a legacy of misery, caused entirely by these “horrendous machines”, which will surround Scotland’s coasts like “the bars of a prison”.
Trump’s fight against the “insanity” is motivated, apparently, by a wish to honour his Scottish mother. The bizarre and emotional language suggests a man in the grip of strong emotions. People like him who see themselves as “hard-headed businessmen” often suppress emotion and, consequently, when it does emerge, it flows out like a volcanic eruption, as suggested by the highly charged language.
Perhaps his Scottish heritage is very important to Donald Trump, and, as he approaches old age, he is, like many people, drawn to his roots – although in a Scotland he wishes to be unchanging. Perhaps he sees Scotland as the mythical land of Brigadoon – or perhaps of the film Local Hero, in which there is an American entrepreneur, reminiscent of Trump, who becomes a local benefactor. The implication of Trump’s tirade, though, is that, by changing the landscape of his dreams, Mr Salmond is somehow attacking him personally.
The signature looks as though it was written by a child using a felt-tip pen, which goes with the whole tone of the letter – somebody who has reverted to childish behaviour. There is the view that people who have the type of businessman personality – emotionally controlled, very driven – flip into the opposite when they get stressed: they become childish and driven by their emotions.
I imagine that, like many of us who fire off angry letters while in the grip of emotion, he is probably regretting his angry outburst. But in his case, the outburst might not be so easily forgotten by his opponents.
• Dr Mary Brown is a lecturer in psychology at Robert Gordon University in Aberdeen.