[ ا ] is designated as a Hamzah Wasl [Conjunctive Hamzah] when it occurs between one of the three short vowels [ ـَـِـُ ] and a Sukun.
Hamzah Wasl at the beginning of a word is not pronounced if there is no pause before the word (i.e. when there is continuous reading).
Hamzah Wasl is not pronounced when preceded by a particle such as [ و ] in [ والفجر ].
Hamzah Wasl is written in the `Uthmanic calligraphy of the Qur"an in a special shape as shown in the examples.