Severe weather is caused by temperature and which other two physical factors?

Severe weather signifies any threatened meteorological occurrence with the likelihood to cause serious social disruption, destruction, or loss of human life. The kinds of severe weather phenomenon differ, on the basis of altitude, latitude, atmospheric conditions, and topography.  

Hail, high winds, wildfires, and excessive precipitation are the kinds and influences of severe weather, likewise, tornadoes, thunderstorms, cyclones, and others are. The key variables that influence that how the weather will behave are temperature, air pressure, and density of the air.  

where is the scientific experiment?