From The Encyclopedia of Earth
Meteorology (Meteorology) Last Updated on 2014-10-26 16:32:04 Meteorology is the scientific study of the atmosphere and physical processes of interaction with the Earth's crust, oceans and outer space. Meteorological phenomena are observable weather events which are investigated by the science of meteorology. The chief parameters comprised by the science of meteorology are: temperature, barometric pressure, humidity, sunlight and the gradients and interactions of each variable, as well as their temporal variability. The majority of Earth's observed weather is located in the troposphere. Different spatial scales are studied to determine how systems on local, regional, and global levels impact meteorological phenomena. Meteorology, climatology, atmospheric physics and atmospheric chemistry are sub-disciplines of the atmospheric sciences. Meteorology and hydrology compose the interdisciplinary field of hydrometeorology. Interactions... More »
Clouds (Meteorology) Last Updated on 2014-09-30 10:52:27 A could is a visible aggregate of minute water droplets or ice particles in the atmosphere above the Earth's surface. Clouds are classified according to their height above and appearance (texture) from the ground. Clouds form when air is cooled to its dewpoint—or the temperature at which, if the air is cooled, it reaches saturation with water. Air can reach saturation in a number of ways. The most common way is through lifting. As a bubble or parcel of air rises it moves into an area of lower pressure (pressure decreases with height). As this occurs the parcel expands. This requires energy, or work, which takes heat away from the parcel. So as air rises it cools. This is called an adiabatic process. The rate at which the parcel cools with increasing elevation is called the "lapse rate". The lapse rate of unsaturated air (air with relative humidity <100%)... More »
Von Humboldt, Alexander Last Updated on 2014-06-26 16:40:53 Baron Alexander von Humboldt (1769-1859) was one of the last true generalists in science. While generally considered a geographer, he contributed to most of the sciences of the natural environment found today. Born in Berlin, von Humboldt’s father was Chamberlain to the King, a royal advisor, who died when Alexander was nine years old. As a child, he received a private education and was a slow learner and sickly much of the time. On his own, though, he loved collecting local plants and animals and reading books on foreign travel and adventure. He also loved to draw, mostly landscapes. Typical of the time, science was not part of his schooling; Humboldt was generally self taught in that area. At sixteen, he attended some lectures on physics and philosophy by a local doctor and then he decided to pursue a career in science. Humboldt... More »
Seed dispersal of desert plants Last Updated on 2014-06-24 19:28:08 Seeds generally need to be transported some distance from the parent plant in order to find a suitable site for establishment. Some plants have wind-dispersed seeds, which are occasionally blown many miles from their origins. This means of dispersal is common among pioneer plants (plants that are adapted to colonizing disturbed habitats). Because of their superior ability to invade newly-disturbed ground, pioneer plants comprise many of our agricultural and garden weeds. Moreover, most annual crops are domesticated pioneer plants. That’s why we need to plow (disturb) fields in order to grow them. Many plants use animals to disperse their seeds in another complex coevolutionary process. Small, brightly-colored fruits such as hackberry and boxthorn are offered as food for birds that swallow them whole. Other fruits such as those of hedgehog cacti are large and... More »
Earth's atmospheric air Last Updated on 2014-04-02 14:56:48 The Earth's atmospheric air is a colorless, odorless and tasteless mixture of gases consisting mostly of nitrogen (N2) and oxygen (O2). It is the part of Earth's atmosphere that humans and all other animals breathe in order to obtain the oxygen needed to sustain life. The Earth's atmosphere not only contains the air we breathe, it also holds clouds of moisture (water vapor) that become the water we drink. Furthermore, it protects us from meteors and harmful solar radiation and warms the Earth's surface by heat retention. In effect, the atmosphere is an envelope that protects all life on Earth. The air may contain pollutants that originate from a variety of sources such as our industries and our vehicles, and can directly or indirectly affect our health and the natural environment. These effects may be experienced near the sources of air pollution and some air... More »
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