In Arabic, letters (or more accurately phonemes) are categroised into two categories: Sun letter and Moon letter in regard to what happen if we add Al (the) to them.
Moon letters don't cause any change to the word's pronunciation. For example, Al-Qamar (the moon) is actually pronounced how it is written. However, in the case of a word like Al-Shams (the sun) the l is not pronounced and the consonant sh becomes a doubled consonant (pronounced twice).
I was wondering about the phonetic reason for that phenomenon. What makes a native speaker of Arabic do this? Are some letters faster to pronounce twice rather than pronouncing an L before them instead? Or is that due to another reason?