Related Clues:

• Wave down, as a taxi
• Stones from the sky
• Environmental awareness topic
• Cab signal
• Ecological danger
• ''Ave!''
• Greet with acclaim
• Balls of ice
• Summon, as a cab
• Honor, as a military hero
• Word with ''stone'' or ''storm''
• Low-pH precipitation
• Call to
• Golf-ball-sized precipitation, maybe
• Corrosive stuff from the sky*