AIR CIRCULATION: 

• Warm air expands (density decreases) and rises up leaving an area of low pressure.
• When air goes up through upper layers of the atmosphere cools down (se enfria). 
• Cold air contracts going down into the atmosphere, generating a high-pressure area.
• From high pressure area, air flows near Earth’s surface to low pressures, warming up. 
• The circuit which air flows continuously: convective cell.
• If Earth were motionless, air circulation would follow convective cells that would extend

1.Ecosystems and environmental factors.Ecosystem:is a system formed by a group of organisms of different species(or biocenosis),the environment in which they live and its physical/chemical characteristics(or biotope) and the interactions.Types of environmental factors.Abiotic factor:are the physical/chemical components of an ecosystem(temperature,light,water).Biotic factors:interactions produced in the biocenosis(wolves when they hunt as a pack).Tolerance ranges and limiting factors:an environmental

SALES AND MARKETING FUNCTIONS:  includes all activities necessary to bring consumers the goods or services produced by the company, thus satisfying their needs and trying to achieve the best results. (a product is sold if there is a good marketing policy that publicizes and makes it desirable.Duties of the sales and marketing department: planning and control, market research, product promotion and advertising, sales.THE MARKET: is defined as a set of purchasing and sales activities of a product