There are some things that it’s next to impossible to remember, like the fact that ‘separate’ only has two Es in, the fact that I don’t have milk in my tea, and which way round longitude and latitude are. At least, I find it so: I accidentally put milk in my own tea sometimes, and the other two are particular weaknesses of mine.
Latitude-wise (whichever -wise that is, I can’t remember), the problem is that most mnemonics aren’t very good. They encode something like ‘north to south’ or ‘west to east’ – for example, ‘lat’ rhymes with ‘flat’, and we naturally think of lines from west to east as flat. But are we remembering the line along which latitude is constant, or the line along which it varies? I can never remember. For a mnemonic to work for someone as thickheaded as I can be, it has to indicate that as well.
So here is my foolproof (not actually foolproof) method by which anyone (or possibly just me) can easily (or maybe with difficulty) remember (or not) quickly (eventually) which one is longitude and which one is latitude:
‘Latitude’ is a very close anagram of ‘altitude’. Altitude changes when you go up and down, and, if north is up, so does altitude.
You can tell this is an excellent mnemonic, because whenever I check Wikipedia to make sure that it’s right because I don’t trust it enough, it turns out that it is.
Unless it isn’t. Let me check again.