Question: what three conditions are required for thunderstorms to form
[{'answer': 'Moisture', 'provenance': [{'wikipedia_id': '70807', 'title': 'Thunderstorm', 'start_paragraph_id': 6, 'start_character': 210, 'end_paragraph_id': 6, 'end_character': 218, 'bleu_score': 1.0, 'section': 'Section::::Life cycle.\n'}]}, {'answer': 'An unstable airmass', 'provenance': [{'wikipedia_id': '70807', 'title': 'Thunderstorm', 'start_paragraph_id': 8, 'start_character': 13, 'end_paragraph_id': 8, 'end_character': 32, 'bleu_score': 1.0, 'section': 'Section::::Life cycle.\n'}]}, {'answer': 'A lifting force ( heat )'}]