Let’s compare the 'short a' /æ/ and 'short o' /ɑ/, the sounds in the words ‘hat’ and ‘hot.’ Both of these sounds are horribly named because they are NOT quick or ‘short’ sounds. I continue to use their historic names so you can find more information from sources other than me on the Internet. /æ/ and /ɑ/ are just the common spoken names used for the sounds /æ/ and /ɑ/. The critical thing to remember that neither /æ/ nor /ɑ/are quick, little sounds. They’re most likely to occur on stressed or secondarily stress syllables or single-syllable words. Practice with minimal pairs.