Explanation: The rank-size rule defines range as the longest distance that a customer will travel to purchase a good or service. Threshold is the minimum market needed to support the supply of a product or service. It is assumed that customers which travel longer distances to purchase a higher-order good or service, and a provider of such goods and services will require a larger customer base to make a profit. Thus, higher-order services have larger ranges and thresholds.
The greenhouse effect is the process in which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere. Radiatively active gases in a planet's atmosphere to make heat
culture include increasing cross cultural interaction; understanding, maintaining and keeping local culture, arts, crafts and traditions; empowering host communities; and strengthening cultural values.
