chapter  15
27 Pages


Weather data come chiefly from weather observing stations on land, and from ships at sea (Figure 15.1). Measurements are made of pressure (Section 1.5), temperature (Section 3.1), humidity (Section 6.3), rainfall (Note 10.B) and wind (Section 14.1). Other readings are taken of visibility, lightning and thunder, and cloud cover at three levels of the troposphere. In addition, there were about 600 buoys drifting at sea by 1992, and another 200 or so moored, measuring air and sea-surface temperatures and pressure, and then transmitting the data to passing satellites for later relay to ground receivers. Weather radar is now widely used, especially near cities, to monitor rainfall, wind and temperature (Note 15.A).