Related Clues:

• Contents of a sensitive layer
• Thunderstorm residue
• Fragile layer
• Pure air
• Oxygen form
• Protective layer
• Earth's ___ layer
• Protective layer makeup
• Thunderstorm byproduct
• Ultraviolet blocker
• Gas in a layer
• Atmospheric concern
• Makeup of a protective layer
• Atmosphere layer
• Layer with a hole