Ecosystems have always been subjected to change. Under the impact of anthropogenic influences, change may beaccelerating in many ecosystems. Some are deliberately created, others are a consequence of humanactivities. Weather modifications Artificial rain making Desalination Green House Effect Destruction of ozone umbrella Acid rain
It is the act of intentionally manipulating or altering the weather. The most common form of weather modification is cloud seedingto increase rain or snow. Weather modification can also have the goal of preventingdamaging weather, such as hail or hurricanes, from occurring. It includes Cloud seeding and production of artificial rain Fog dissipation Frost prevention Lightning and hail suppression
Is the act of attempting to artificially induce or increase precipitation. Process of normal rain fall….. Rainfall occurs when cloud droplets grow large enough to fall to earth. Growth of cloud droplets occurs around a cloud seed. Cloud seeds or cloud condensation nuclei (CCNs) are small particlestypically 0.2μm about which cloud droplets coalesce. No CCN – no rainfall Cloud seeding is a process which attempts to change the amount or typeof precipitation that falls from clouds, by dispersing substances into theair that serve as CCN.
Any technique of cloud seeding depends on the release of millionsof tiny particles of dry ice or silver iodide into a cloud. Methods Ignite solid silver iodide in burners on the ground. The smokethus formed consists of many tiny particles of the compoundwhich are then carried upward into a cloud. Dropping the seeding agent from an airplane onto the top of thecloud (spraying) The particles are fired into clouds from aircraft-mounted flareguns at a height of over 2,000m. Cloud seeding is the most common method of rain making.
Dry ice grains with high-pressurized air at almost sonic speedis blasted into the fog. The dry ice grains collide with the fog droplets, acts as aseeding agent The fog droplets grows in size and precipitates out of air. Thus fog may disappear. It can be applied anywhere where fog hinders functioning likeairports, roads, harbours etc.
Hail - devastating effects on crops Hail can be prevented if the atmosphere is flooded with nuclei onwhich moisture can condense and freeze. The more nuclei present, the less likely large pieces of ice (hail)are to form. Relatively little work is now being done in the field.
Desalinisation is the process that remove salt and other mineralsfrom saline water to create fresh water. Imp in places where availability of freshwater is limited. One potential byproduct of desalination is salt. 2 main methods Multistage flash distillation Reverse Osmosis (Membrane desalination process)
Water is heated in a container called brine heater. The heated water then flows to a second container called stage,where pressure is lower. Low pressure causes water to boil, some part forms steam The remaining water is moved into the next stage. The vapour produced is condensed in tubes of heat exchange. Same process repeated, so produces clean water & brine.
It is done by reverse osmosis (RO) Reverse osmosis is a process where the solvent molecules moveacross a semi permeable membrane from high soluteconcentration to low solute concentration. It requires input of energy. A RO membrane is a semi permeable membrane that allows thepassage of water molecules but not majority of dissolved salts andother larger molecules. Saltwater is forced through membrane sheets at high pressures(600 to 1000 psi) Process produces clean water and brine
A greenhouse is a glasshouse inwhich plants are grown in coldercountries. Principle The suns energy enters through thegreenhouse glass easily, plants absorbit and utilize it. A part of the radiation is re -emittedby the plants and soil It cannot get out as easily thus heatgets trapped inside. Earth’s atmosphere acts as a greenhouse.
Incoming solar radiations passesthrough the atmosphere andreaches earth’s surface.The earth’s surface absorbs the solarenergy and releases it back to theatmosphere as IR radiations some of whichgoes back into the space.Some of the IR radiations emitted bythe earth is absorbed by green housegases in the atmosphere & theyre-emit the energy as heat towardsthe earth’s surface.This increases earth’s surfacetemperature and this processis known as ‘Green House Effect’.
GREEN HOUSE GASESWater vapour: It is responsible for about two-thirds of the naturalgreenhouse effect. A part of water cycle.Carbon dioxide: Main contributor to the enhanced (manmade) GHE Globally, it accounts for over 60% of Enhanced GHE. The major source - from the burning of fossil fuelsMethane: Mining and burning of fossil fuels, livestock husbandry ,rice cultivation – major contribution. Methane can trap heat 23 times more effectively than CO2.
Nitrous oxide (N2O) Is released naturally from oceans and rainforests and by bacteriain soils. Human-influenced sources include nitrogen-based fertilisers,fossil fuel combustion and industrial chemical production.Fluorinated greenhouse gases: These are the only greenhouse gases that do not occur naturally,but have been developed by man for industrial purposes. Share - around 1.5%. But they are extremely powerful can trap heat up to 22,000 times more effectively than CO2 can stay in the atmosphere for thousands of years. The best known of these gases are chlorofluorocarbons (CFCs),which are not only fluorinated greenhouse gases, but also depletethe ozone layer. They are being phased out under the 1987 Montreal Protocol onOzone Depleting Substances.
CAUSESEvaporationEnhancedGreenhouseeffectANTHROPOGENICNATURALVolcaniceruptionsMethane gas fromcattle dung.Burning of fossilfuelsDeforestationUse of fertilizersCFC’s from AC ,fridges etc
Enhanced GHE would lead to global warming and other climatechanges. Due to rise in global temp oceans will become warmer – affect livingorganisms. Melting of glaciers and polar ice caps will lead to rise in sea level andflooding of many low lying areas – islands at the risk of submergence. Several plant and animal species will become extinct due to theirinability to adjust quickly to new conditions. Coral reefs would be severly threatened. Water scarcity & drought. Spread of several diseases. Extreme weather events – rising intensity of floods, droughts, stormsetc.
We are running out of timeact now beforeits too late.Reduce fossil fuelconsumption.Use of cleaner energysources.Energy efficientpractices.Preservation and maintenanceof existing forestsPlant more trees.Better agriculturepractices.SOLUTIONS
Humans have been interacting with ecosystems and modifyingthem for as long as human life has existed on Earth. The scale, speed and degree of change that is occurring threatensthe survival and integrity of many ecosystems and also humanlife. The number of human-induced modifications to ecosystemshas increased as population and technology has increased. Its high time we address the consequences and takeappropriate steps to reduce the impacts.
Using supercomputers, MIT (Massachusetts Institute ofTechnology ) researchers have come up with a newapproach for desalinating water–using sheets of graphene, aone-atom-thick form of the element carbon Graphene sheets with precisely controlled pores havepotential to purify water more efficiently and lessexpensively than existing methods.
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