The division of labor occurred as surplus food supplies provided people with greater stability and security. This development enabled societies to become more sophisticated and to develop culturally. Complex social classes emerged; many social classes developed, including a ruling nobility and a priestly class. Other classes, such as artisan classes, developed based on skills. Organized religion also emerged. Religion was commonly polytheistic, initially with gods who focused on basic human desires and fears like fertility, death, and the weather. Recordkeeping and the first writing systems were other developments. Governments and tax collection came into existence, and cities organized military units and created military structures, such as moats, to protect themselves from invaders.
Maritime tropical air masses that influence the weather of the western coastal areas of the America starts in the Caribbean Sea, then to the southern Gulf of Mexico, and the tropical Atlantic east of the Florida and the Bahamas.
Maritime tropical air masses are moist and unstable. While the continental dry air mass consisting of the hot and arid climates of the southwest, thus their interaction creates occasional thunderstorms.
