.... and emergency vehicles. Salt is used as the principal deicer because it is the most available and cost-effective deicer. Rock salt is preferred because it is cheap and effective. It costs 20 dollars a ton where as an alternative like calcium magnesium cost around 700 dollars a ton. Some 10 million tons of deicing salt is used each year in the U.S. and about 3 million in Canada. Salt is used to keep snow and ice from bonding to the pavement and to allow snowplows to remove. When salt is applied to ice and snow it creates a brine that has a lower freezing temperature than the surrounding ice or snow. Salt is the ideal deicing material because it is: •the .....

.... organisms are neither plants nor animals. The limits of the science, however, have always been difficult to determine, and as the scope of biology has shifted over the years, its subject areas have been changed and reorganized. Today biology is subdivided into hierarchies based on the molecule, the cell, the organism, and the population. Some of the more specific types of biology are as follows: Molecular biology, which has made the most fundamental contributions to modern biology; Cellular biology, which is closely linked with molecular biology. Cellular biology deals with the functions of the cell and the basic strucural unit of living matter; Finall .....

.... Darwin called this process natural selection. Darwin did not understand how or why variation existed. Today scientists realize that variation arises through random changes (called mutations) to existing genes. Genes are the chemicals that determine the traits and characteristics of animals and plants. Every trait has one or more gene associated with it. Thus, natural selection provides the animals and plants with the best genes. Supporters of neo-Darwinism believe that natural selection operating upon random variation gave rise rise to all animals and plants. While the source of variation is random, the direction of evolution is not. In .....

.... is usually very short. It depends on how high the tide is which goes up and down twice a day. When the velocities of hurricane winds become severe the height of the waves become three or more feet higher than the previous high tide. Coastal floods can be caused by a number of things. Coastal floods can be caused by runoff, hurricane waves, tsunami (seismic sea waves), and hurricane rains. Coastal flooding can not only take part on oceans but it can also take part on lakes. Coastal flooding can be a great danger because coast lines are very densely populated areas. In the United States in the early 1990's 50% of the population was on a coastal county.1 Although .....

.... control. If this goal were achieved, the environmental problems would be minimized, and significant benefits would result for farmers and society as a whole. IPM coordinates economically and environmentally acceptable methods of pest control with judicious and minimal use of toxic pesticides. IPM programs assess local conditions, including climate, crop characteristics, the biology of the pest species, and soil quality, to determine the best method of pest control. Tactics employed include better tillage to prevent soil erosion and introduction of beneficial insects that eat harmful species. Many pests that are attached to crop residues can be eliminated by .....

.... and Cold Polar climates are marked by certain prevailing characteristics that can be mapped such as continuous snow or deserts. One of the most popular classification systems is the Koppen Climate Classification system, which gives different climates three letters that describe that climate. The Koppen Climate Classification system is comparatively simple and is based on a triad of letter symbols. The first (capital) letter is the critical one; the A climates are humid and tropical; the B climates are very dry; the C climates are humid and mild; the D climates reflect increasing cold; and the E climates mark the polar areas. The first letter is .....

.... relatively permanent and limitless storehouse. Humans also have short-term memory, which is activated memory that only holds a few items briefly, things such as the seven digits of a phone number while dialing, before the information is either stored or forgotten, activated human activity memories rapidly decay unless used or rehearsed. Encoding can be an automatic process, this occurs when little or no effort, without awareness, and without interfering with our thinking about other things. Encoding can also be effortful processing; although we encode an enormous amount of information unintentionally, many other types of information we remember only with muc .....

.... it is and what it does. When ultraviolet light from the sun hits the earth's atmosphere, it hits and divides the oxygen molecule (O2). Each molecule then attaches with other oxygen molecules to form O3. O3 is ozone. So when ozone is formed, harmful rays from the sun are absorbed. The O3 molecule is very reactive and it bonds easily with other molecules it the atmosphere. When and oxygen atom from the ozone reacts with a chloride ion from chlorine monoxide, the ozone molecule is destroyed. So chlorine monoxide is an ozone destroyer. There is always a certain amount of chlorine monoxide in the atmosphere. It is important to remember that ozone is constantly be .....