Weather balloon Weather balloon A weather or sounding balloon is a balloon (specifically a type of high-altitude balloon) that carries instruments aloft to send back information on atmospheric pressure, temperature, humidity and wind speed by means of a small, expendable measuring device called a radiosonde. To obtain wind data, they can be tracked by radar, radio direction finding, or navigation systems (such as the satellite-based Global Positioning System, GPS). Balloons meant to stay at a constant altitude for long periods of time are known as transosondes. Weather balloons that do not carry an instrument pack are used to determine upper-level winds and
Zero-profit condition Zero-profit condition In economic competition theory, the zero-profit condition describes the condition that occurs when an industry or type of business has an extremely low (near-zero) cost of entry. In this situation, many people tend to join the industry, seeing the opportunity to make money, until there is no more money to make (supply exceeds demand); the large amount of competition limits each person's share of the market, as well as their ability to pursue a large profit margin. This would represent a situation of almost perfect competition. For instance, despite the real estate boom of the mid-2000s, the incomes