the atmosphere and human activities Flashcards
what is the composition of the atmosphere divided into?
nitrogen: (78.09)- for growth of plants
oxygen: (20.95)- produced by photosynthesis, used in respiration
water vapor: (0.2-4)- precipitation, vital for existence of life
carbon dioxide: (0.03)- used by plants in photosynthesis
argon, helium, neon, krypton: (0.93)- creates inert atmosphere that prevents materials from reacting with oxygen
the structure of the atmosphere:
- in all layers of the atmosphere, pressure decreases as height increases. atmosphere is divided in 4 layers:
troposphere: 0-18km, 15- -56 celsius. temp decrease with height as convection of heat from earths surface decreases. top of layer is called tropopause. this is the limit to earths weather and climate
stratosphere: 11-50km, -56- -2.5 celsius. temp increases slightly with height and this is known as temp inversion. this happens due to the concentration of ozone that absorbs suns ultraviolet rays. shield against incoming meteorites
mesosphere: 40-90km -2.5- -86.5 celsius. temp falls rapidly as there is no dust or water or ozone
thermosphere: 80-800km -86-1200 celsius. temp rises rapidly due to absorption of ultraviolet radiation by atomic oxygen.
exosphere: 800-3000km 1200 celcius. outer space
what is the natural greenhouse effect?
a process that helps keep the earths surface and atmosphere warm.
- the earth receives short wave radiation from the sun. half of this radiation is absorbed by the earths surface. 20% absorbed by atmosphere. greenhouse gasses absorb some of this radiation and deflect it back into the earths surface
what are examples of greenhouse gasses?
natural: water vapor, carbon dioxide, ozone, methane
artificial: chlorofluorocarbons (CFCs)
the more the concentration of greenhouse gasses, the more effectively they return radiation back to the earth.
what are the greenhouse gases contribution to greenhouse effect and number of years the gas stays in atmosphere?
carbon: 65%, 200 years
methane: 17% 12 years
CFCs: 12% 1000 years
nitrous oxides: 6% 114 years
what are the causes of atmospheric pollution?
acid rain: precipitation with PH value of less than 7- burning of fossil fuels release greenhouse gases like nitrogen oxides and sulfur dioxide that are blown over long distances and mix with water vapor in the atmosphere to form acid rain.
smog: burning of fossil fuels provides particles like smoke and dust for fog to form around
photo chemical smog: involves chemical reactions induced by sunlight on certain pollutants. these reactions convert them into harmful substances like tropospheric ozone (bad ozone)
enhanced greenhouse effect: addition of greenhouse gases to atmosphere. more heat is retained in the atmosphere as the gases trap the suns heat and energy, contributing to global warming.
Volatile organic compounds: chemicals that easily enter the atmosphere as gases, mainly from evaporation (methane)
temperature inversion: when the air temp increases with altitude rather than decreasing
explain how and why temp inversion occurs?
during the day, the surface is heated due to long wave radiation. on clear nights, the earths surface cools quickly emitting radiation and cooling the air above it. at high altitude, the air doesn’t cool as quickly as large amounts of warm air rises so the air becomes warmer than the air below it by accumulating. this layer of warm air is the inversion layer which disrupts regular convection currents
what human activities increase the amount of greenhouse gases?
carbon: deforestation, burning of fossil fuels
methane: cattle and rice production, decomposition of waste (landfill sites)
CFCs: fire extinguishers, air conditioning
nitrogen oxides: fertilizer, vehicle exhaust
explain the ozone layer depletion:
the ozone protects the earth from the harmful radiation of the sun.
- it is formed when oxygen filters from the top of the troposphere and reacts under influence of ultraviolet radiation to form ozone (O3)
- it is continuously renewed, and destroyed.
when CFCs reach the stratosphere, the ultraviolet radiation breaks them down releasing chlorine.
- this chlorine reacts with oxygen in a destructive process, breaking down ozone molecules to chlorine monoxide and oxygen, depleting the layer and forming a hole
- this allows harmful radiation to enter the earth.
impacts of atmospheric pollution:
smog; respiratory disease, lung cancer, breathing issues, irritation of eyes and throat
acid rain: bad for organisms in lakes. bad for land (releasing aluminum in soil), if the water is consumed it can cause diarrhea, crop yields decline
ozone depletion: skin cancer, retina damage, limits reproduction of phytoplankton which affects entire food web
climate change: melting of ice sheets and glaciers which contribute to increase in sea level, loss of biodiversity, drought,
how is photochemical smog made?
nitrogen oxides from vehicle exhaust and volatile organic compounds, undergo photochemical reaction in the presence of sunlight and heat to make smog
