thunder is a mean of sunny potential
degree_of_storminess is weather_attribute. lightning is not meteorological_event. sunny is one_type_of_weather. lightning is meteorological_event. sunny_days is not brighter_than_cloudy_days. blowing is meteorological_event. thunder is extreme_form_of_weather. sunny is not one_type_of_weather. sunny_days is brighter_than_cloudy_days. thunderstorm is rainstorm.