Answer to Question 1
Answer: These images are obtained by sensors on board the satellite that measure the amount of radiation received at two particular wavelengths of electromagnetic energy, 6.7 microns and 7.3 microns. Water vapor is effective at emitting and absorbing these wavelengths from the Earth's surface. At the same time, energy at 6.7 microns and 7.3 microns emitted by water vapor in the middle of the troposphere escapes to space and is observed by the satellite.
Answer to Question 2
Answer: The simplest and most widely used instrument for measuring humidity, the sling psychrometer, consists of a pair of thermometers, one of which has a cotton wick around the bulb that is saturated with water. The other thermometer has no such covering and simply measures the air temperature. The two thermometers, called a wet bulb and dry bulb thermometer, respectively, are mounted to a pivoting device that allows them to be circulated (slung) through the surrounding air. If the air is unsaturated, water evaporates from the wet bulb, whose temperature falls as latent heat is consumed. After about a minute or so of circulating, the amount of heat lost by evaporation is offset by the input of sensible heat from the surrounding, warmer air, and the cooling ceases. Thereafter, the wet bulb maintains a constant temperature no matter how long the instrument is swung around.
Electron Microscope Images of a Diatom
Layers of Rock Laid Down by Water
Clinal map of the distribution of HbS in Africa.
Water on Mars!
Distribution of Rods and Cones on the Retina
Running Water