Scottish vowel length rule

The Scottish vowel length rule describes how vowel length in Scots, Scottish English, and, to some extent, Ulster English and Geordie is conditioned by the phonetic environment of the vowel. It is also known as Aitken's law in reference to the Scottish linguist A. J. Aitken, who formulated the generalization.

Source: Wikipedia — Scottish vowel length rule (CC BY-SA 4.0)