الّلام الشمسية والقمرية
To make a noun definite or specific, we need to add an article like “The” in English, this is the “AL” in Arabic that precedes many nouns ال. Shamsi and Qamari letters change the way you pronounce “AL”. They are also called Sun (shamsi) and Moon (Qamari) letters.
If a noun has “AL” and the first letter of the noun is a Shamsi letter, then the “Lam” of AL is not pronounced.
And in this case, this letter “Lam” ل is called a Shamsi Lam لام شمسيه. The first letter of the word following the Lam is also stressed or doubled.
If the first letter of the word is a Qamari letter, the “AL” is pronounced normally followed by the word. This is called لام قمريه
The Shamsi and Qamari letters
A lot of people find it easier to only memorize one type of letters, usually the Qamari ones, then the rest of the 28 Arabic letters are all Shamsi.
A common mnemonic to help people remember them is this sentence, all the letters are the Qamari ones:
ابـــغ حجك وخف عقيمه
So the Qamari letters are:
أ ب غ ح ج ك و خ ف ع ق ي م ه
Examples of Sun and Moon letters:
The following are words starting with a Qamari letter and when you add “AL”, the ‘Lam” is pronounced:
Examples of words starting with a Shamsi letter, leading the “Lam” in “AL” to be silent:
How to differentiate between them without memorizing?
It is often memorized but the main thing is to keep practicing, specially listening to native speakers. Another way to try to guess the type of the letter, is to assume it is a Shamsi letter, and try pronounce the word as if it was, a Qamari letter would sound and feel very unnatural and difficult to pronounce. However, this needs some little of experience.
Here are all the letters in the Arabic alphabet divided according to their type:
What if the first letter is a “Lam”?
Just like any other letter, “Lam ل” is a Shamsi letter, so you are supposed to drop one “Lam” in “AL” but then stress the first letter of the word which in this case is the same: ل. So basically, you just treat both as one stressed Lam. I found this video on Youtube (and many others) which could be helpful. There is one mistake in the video which is the letter س is actually Shamsi and I think it was just a typo and it was meant to be a “yaa”ي.
Please let me know if you have any questions.