Ȧ (minuscule: ȧ) is a letter of the Latin alphabet, derived from A with the addition of a dot above the letter. It is occasionally used as a phonetic symbol for a low central vowel, IPA: [ä]. Despite the character only added a dot above, it is not easy to show up in computers. It is used in Livonian language.
References
Pullum, Geoffrey K.; Ladusaw, William A. (1996). Phonetic Symbol Guide. University of Chicago Press. p. 3.