How do clouds form? Main types of clouds. Precipitation. Air Pressure. What are the Four Most Influential Air Masses that Affect the Weather in North America? What is needed for a thunderstorm to occur? Thunderstorm key ingredients: Moisture, Instability and Uplift. What is a hurricane? What is a tornado? What is climate? Climate Zones: Polar zone, Temperate zone, Tropical zone. The location of the zone determines its climate. Read More...