What is greenhouse effect?

The theory of the greenhouse effect is that certain gases concentrate in the atmosphere, where they function as an insulating barrier, absorbing infrared radiation that would otherwise be reflected back into the upper atmosphere. In other words, like glass in a greenhouse, the gases let in incoming solar radiation but retard its reradiation back into space. The greenhouse effect could cause a gradual warming of the earth's surface and the lower atmosphere. Higher temperatures would have significant impacts on the earth's ecosystems.

What gases are we taking about?
Carbon dioxide. created mostly by burning fossil fuels, is the most plentiful of the gases and is thought to be responsible for about half of the warming. Each year, we send about 5.6 billion tons of CO2 into the atmosphere, only half of which is absorbed by the oceans and forests. Burning the tropical rain forests not only adds to the emissions but also means losing trees that naturally absorb CO2.

Acid Rain Prevention - Fill Up Wisely

The way you fill up your car affects the amount of nitrogen oxides the car produces. The fewer emissions, the less acid rain.

If you have an old "gas guzzler" that uses leaded fuel, consider getting rid of it. Leaded gas is laden with nitrogen oxides. Even if you can't afford to trade it in, you may be able to use unleaded gas or a mixture of leaded and unleaded high octane. Check with your mechanic to be sure.

If you have a car that uses unleaded fuel, be sure to fill it with unleaded. Leaded gas can ruin a newer car's catalytic converter, which is designed to reduce nitrogen oxide emissions.

Vapor controls are there to prevent vapors from escaping into the atmosphere. Don't pull them back; the vapors help create smog.

Don't "top off" the gas tank. Stop when the nozzle clicks off. Topping off will force gas fumes into the atmosphere.

Cars don't have to run on a petroleum-based fuel. If you live in an area where alternative clean fuels are available, try one of them. Fuels such as ethanol, methanol, and natural gas burn more clearly that conventional gasoline and produce fewer nitrogen oxide emissions. Although methanol and natural gas come from nonrenewable resources, ethanol can be made from a variety of renewable ones, such as corn, sugarcane, or grains. Gasohol, a blend of ethanol and gasoline, can be used in any vehicle without engine modifications.

Finally, don't buy a car that uses diesel fuel. Even though diesel engines conserve fuel, they produce far more pollutants than do other cars and won't meet emission standards in states that have them.

Acid Rain - Get Better Gas Mileage

Motor vehicles produce from one-third to one-half of nitrogen oxide emissions in North America. That's why individuals can help stop the acid rain problem. The less gas we use, and the cleaner the gas, the fewer nitrogen oxide particles will be spewed from tailpipes. Of course, we would all benefit by driving less, but if you must use a car, here are some ways to make sure its impact on the environment is as benign as possible:

• If you are considering buying a new car, got one that is fuel efficient - that gets at least the average number of miles per gallon. The standard for 1990 cars is almost 28 miles per gallon, but you can buy cars that get 40 mpg or 50 mpg. The more miles you get per gallon, the fewer emissions your car will produce.
• Consider a manual transmission as opposed to a automatic transmission. You will use less gas.
• Make your car more fuel efficient by having it tuned up every 5,000 to 10,000 mile. Make sure the fuel filters and spark plugs are clean. Change the oil regularly. You will increase the fuel economy of your car by as much as 15%.
• Check once a month to make sure your tires are inflated to the maximum pressure intended by the manufacturer. It is estimated that about half of American cars have underinflated tires. Because underinflation increase resistance, it wastes gas.
• If you need new tires, check out steel-belted radials, which can increase fuel efficiency by 5% to 10%.
• Do you really need that air conditioner? It uses gas even when it's not running, it will use as much as a gallon of gas per tankful, increasing your fuel consumption anywhere from 10% to 20%
• Try to reduce the number of car trips you make. Combine several errands into a multipurpose trip. Avoid making many short, single-purpose trips.
• Idling wastes gas. If your car is properly tuned, you shouldn't have to warm it up for several minutes after starting the car. You should be able to wait just a few seconds for the oil to circulate, then drive away. Don't leave the car idling while you are stuck at a train crossing or waiting for a passenger. It takes less gas to restart the car than it does to let it run for more than 30 seconds.
• Avoid jerky starts and stops, which waste fuel. Accelerate and decelerate smoothly and gradually. Minimize braking by slowing down as you approach a red light. It may turn green before you come to a complete stop. Remember, it takes more gas to move the car from a full sto than from even a very slow speed.
• On the highway, try to maintain a steady speed. Fifty-five miles per hour is bes. You will use about 20% more gas at 70 mph than at 55 mph.

Acid Rain

Acid rain is the term generally used for pollutants created by burning fossil fuels that then change chemically as they are transported through the atmosphere and fall back to earth as acidic rain, snow, fog, or dust. The pollutants are chiefly oxides of sulfur and nitrogen, and they come primarily from coal and oil-burning power plants and industries and from automotive exhausts. When sulfur dioxide is absorbed into water vapor in the atmosphere, it becomes sulfuric acid. Sulfur dioxide contributes about two-thirds of the acids in the rain; about one-third come from nitrogen oxides, transformed into nitric acid in the atmosphere.

When the acids are washed out of the air by rain, snow, or fog, they change the pH factor of the soil and water, setting off a chain of chemical and biological reactions. The pH factor measures the acidity/alkalinity of a substance on a scale of 0 to 14. The average pH of normal rainfall is 5.6, but acid rainfalls with a pH of 2.4 - approximately the acidity of vinegar or lemon juice - have been recorded. It is important to note that the pH scale is logarithmic, so that 4.0 is ten times more acidic than 5.0 and one hundred times more acidic than 6.0. Acid rain also coats the ground with particles of aluminum and toxic heavy metals such as cadmium and lead.

Once the pollutants are airborne, winds can carry them hundreds of miles depositing them far from their source. Approximately half of the acid rain that falls on eastern Canada originates in the US, chiefly from the coal-burning power plants in the Midwest. This issue has become a sore point in US-Canadian relations, because the effects of acid precipitation on water bodies, forests, and wildlife are deadly. The problem is that the acidity of a lake or stream need not increases much before it begins to disrupt the food chain.

Canada' Department of the Environment has reported that acid rain has already damaged some 14,000 lakes in that country, rendering them almost fishless; another 150,000 are in peril. Acid rains have also been linked to the disappearance or decline of fish populations in Scandinavia. Some 20% of Sweden's lakes are said to have been damaged by pollution, and much of Norway's fish population has been exterminated.

Acid rain harms soils and vegetation,. It leaches toxic constituents like aluminum salts from the soil and kills micoorganisms in the soil that break down organic matter and recycle nutrients through the ecosystem. Extensive forest damage has occurred in parts of North America, northern and western Europe, The USSR, and China. One can also see the corrosive effects of atmosphere acid on marble and limestone sculptures and buildings and on metals such as iron and bronze.

Much of the responsibility for solving the acid rain problem lies with industry and government, but individuals can help by reducing their demand for energy. Various ways of conserving energy are discussed in a subsequent section, which deals with the greenhouse effect and acid rain is to reduce the emission of pollutants into the atmosphere. We can do that by using less energy and by using it as efficiently as possible,

Smog - Control Harmful Emissions

If you drive

Motor vehicles are the single most important contributor to smog formation, accounting for emissions of both hydrocarbons and nitrogen oxides. You can help prevent smog by using your car as little and as efficiently as possible. We offer some suggestions for reducing gas consumption here:

• Think about you drive. Can you walk, bike, or take mass transit to get where you want to go? Can you combine many short tips into a single, longer one? Can you carpool?
• Have the car tuned every 5,000 to 10,000 miles, and make sure its antismog equipment is functioning properly. If you have a newer car, it probably has a catalytic converter, a cylinder full of metal-coated ceramic pellets through which exhaust gas from the engine is funneled. Its function is to remove hydrocarbons and, to a lesser extent, nitrogen oxides from the exhaust.
• Make sure your tires are properly inflated. Underinflated tires increases resistance and thus waste gas.
• Don't let the car idle unnecessarily when you're starting up, waiting at a train crossing, or talking to a friend.
• Try to maintain a steady speed on the highway, preferably 55 miles per hour. You will use considerably less gas than at higher speeds.
• Try using methanol, ethanol, or gasohol in your car, especially if you live in a region that has smog. They produce cleaner exhaust gases than does gasoline.
• If you have an old car that uses leaded gas, you are spewing hugs amounts of nitrogen oxides into the atmosphere. Ask your service station mechanic whether the car can run on unleaded gas.
• Many state now require that gas pumps be fitted with vapor-recovery nozzles. They make a tight seal with the car's filling pipe and ensure that fuel vapors are returned to the underground tanks at the gas station. Don't pull back the rubber seal.
• Don't "top off" the gas tank. Stop when the nozzle clicks off. Topping off not only forces gas fumes into the atmosphere, it's also likely to result in spilling some gas. The fumes and spilled gas help create smog.

Other things to do

We asked that you think twice before driving anywhere. Also think twice before using any of the following, because all of them emit chemicals that combine to form smog:

• A gas-powered lawn mower.
• An oil-based paint; use latex instead. Oil-based paints contain solvents that evaporate as the paint dries, in the air, they react with other gases and sunlight to form ozone,
• Lighter fluid to start your barbecue grill
• Any aerosol spray, whether it's hairspray, deodorant, or an oven cleaner

Don't some scientists dispute the greenhouse effect?

Yes. Some argue that globe temperatures might stabilize or even decrease as the concentration of greenhouse gases increases. A hotter atmosphere, they say, would increase evaporation, sending u more water vapor that could condense into clouds. The increased cloud cover might reflect so much unlight that it would slow the rate at which the earth would be heated. Others contend that the increased evaporation would produce more rainfall. As it fell, the rain would cool the land and subsequently cool the air over the land.

Finally some researchers believe the geological record shows that large fluctuations in global temperature have always occurred independently of human activity, never as a result of it. these fluctuations are caused by such unpredictable event as variations in solar radiation, shifts in the earth's orbit and in ocean currents, meteoric activity, and volcanic eruptions.