| A | B |
|---|
| Core Temperature | the temperature inside an animal's body |
| countercurrent exchange | the exchange of heat between blood travelling in opposite directions through the arteries and veins that lie side by side. This cools the blood flowing from the center of the body, and warms blood returning to it. |
| crop milk | highly nutritious liquid produced from the lining of the crop in all pigeons (males and females) and feed to the chicks. |
| cutaneous respiration | the exchange of respiratory gases through the skin. Amphibians have a significant portion of their respiration this way. |
| diurnation | a period of dormancy into which an animal enters for part of the day |
| ectotherm | an animal that maintains a constant body core temperature by behavioral means, such as basking in the sun to warm up, or seeking shade to cool down. |
| endotherm | an animal that maintains a constant body core temperature by physiological means, such as dialating or constructing blood vessels, or sweating or shivering. |
| exotherm | an animal that is unable to control its body core temperature, which is equal to the temperature of its surroundings. |
| poikilotherm | an animal that is unable to control its body core temperature, which is equal to the temperature of its surroundings. |
| estivation | a period of dormancy into which an animal enters to escape a period of hot or dry weather. |
| chlorophyll | the pigment in plants that gives them their green color and traps light to provide energy. |
| akle dune | a sand dune in the form of a long, wavy ridge at right angles to the ridge |
| linguoid | dunes that face into the wind |
| barchan | a crescent-shaped dune whose tails point away from the wind |
| angle of repose | the maximum degree of slope at which a pile of dry loose grains remain stable, it is typically between 32 and 36 degrees |
| desert pavement | a thin layer of gravel or small stones that covers the surface of an area of desert |
| draa | a ridge of sand or chain of sand dunes, more than 1,000 feet high, lying some distance from its nearest neighbor, that is found in the Sahara |
| aquifer | an underground body of of permeable material (like sand or gravel) lying above a layer of impermeable material (like clay) that can store water |
| aphelion | the point at which the Earth is farthest in its orbit from the sun. |
| arroyo | a dry river vally with steep sides and a flat floor |
| donga | a dry river vally with steep sides and a flat floor |
| wadi | a dry river vally with steep sides and a flat floor |
| Ouadi | a dry river vally with steep sides and a flat floor |
| artesian well | a well that flows without pumping because it taps into water held under pressure in a confined aquifer |
| butte | an isolated, flat-topped hill made by the erosion of horizontal layers of sedimentary rock |
| clay | mineral material consisting of particles smaller than 0.002 mm that stack together. A clay soil contains at least 20% clay particles by weight. |
| continental drift | movement of the continents in relation to one another across the Earth's surface. |
| desalination | the purification of salt water by the removal of salt to render id fit to use for irrigation or to drink. |
| desertification | the deterioration of land until its quality is similar to that of a desert. |
| desert rose | a petal-shaped rock, sometimes resembling a rose, that results from chemical reactions in calcite (calcium carbonate) and gypsum (calcium sulfate) minerals |
| desert varnish | a thin, dark-colored layer of iron and manganese oxides (rust) that form on exposed rock surfaces in hot deserts |
| dry adiabatic lapse rate | the rate at which the air temperature decreases (lapses) with increasing altitude. In unsaturated air the dry adiabatic lapse rate is 5.38 degrees per thousand feet (9.8 C/km) in saturated air the rate varies, but averages 2.75 F/100 feet, or 5 C/km |
| eccentricity | the extent to which the orbit of a planet departs from a circle |
| ecliptic | the plane of the earth's orbit around the sun. |
| equinox | march 20-21, or Sept. 22-23, when the noonday sun is directly over the equator. Day and night are of equal length. |
| anticyclone | a region in which the atmospheric pressure is higher than it is in the surrounding air |
| climatic optimum | a period during which the average temperatures are higher than the preceeding and subsequent periods |
| cloud seeding | dropping particles of carbon dioxide, silver iodide, or some other substance into a cloud to make rain or snow. |
| convection | the transfer of heat by vertical movement within a fluid (gas or liquid) |
| deposition | the changing of water vapor directly to ice without becoming a liquid first |
| dew-point temperature | the temperature at which water vapor condenses to form dew or cloud droplets |
| El nino | a weakening or reversal of the prevailing easterly winds over the tropical South Pacific Ocean that happens at intervals of 2 - 7 years. This weakens the wind-driven surface ocean current, allowing warm water to accumulate off the South American coast and producing weather changes over a large area. |
| ENSO | the full cycle of el nino and its opposite, la nina, associated with the southern oscillation |
| ablation | the removal of snow and ice by melting or sublimation |
| albedo | the relfectiveness of a surface to light, measured as as the percentage of light reflected |
| blackbody | a body that absorbs all the radiation falling on it, and emits all all of the absorbed radiation at a wavelength inveresly proportional to its temperature. Hotter = shorter waves |
| cyclone | a region along a weather front where the atmospheric pressure is lower than it is in the surrounding air. |
| depression | a region along a weather front where the atmospheric pressure is lower than it is in the surrounding air. |
| anabatic | describes a wind that blows up the side of a hill |
| andhis | a hot, dry, usually dusty wind that blows in spring and summer across the southeastn Sahara and the Arabian peninsula |
| simoom | a hot, dry, usually dusty wind that blows in spring and summer across the southeastn Sahara and the Arabian peninsula |
| deflation | the removal of surface material (such as dry soil or sand) by the wind |
