However, you have to understand how THAL/MTHAL are used. THAL/MTHAL are both a countermeasure to artillery, especially like mortar shells and unguided rockets which are the weapon of choice for guerrilla warfare. Those projectiles do fly very high, and bound to be ineffective during the weather condition that THEL/MTHEL are ineffective. For lightly clouded sky, like covered with scud clouds, THEL/MTHEL are still functional.