a warm air mass slowly passes over a cold air mass above a continent
africa is hot_continent. high is air_mass. continent is land_mass. sun is hotter_than_ocean. land_surrounded_by_water is island_or_continent. hot_air is air. space has no_air thermals is rising_currents_of_warm_air. hot_air is lighter_than_cold_air. air_mass is atmosphere.