FFR166

What do we call "trace gases"? Give at least three examples

The trace gases are mainly CO2, neon, helium, methane, nitrous oxide and ozone.

Explain the basis for the recommendation: if possible, avoid driving your car. When ozone levels are high.

Combustion contribute to the conversion of NO to NO2, increasing the NO2/NO raton and thus ozone production.

Explain how stratospheric ozone plays and important part for life of the earth.

It absorbs solvar UV incoming radiation via photochemical reactions where high energy radiation is taken up and breaking the bonds between oxygen atoms preventing the high energy radiation from reaching the surface.

What role does the global wind circulation play in the earths system?

It evens out the temperature changes we would have without these wind-movements. So warm air travels from the equator towards the poles and cold air travels form the poles towards the equator.

Define and explain the difference between a negative feedback and a positive

"feedback" is a loop of cause and effect that reinforces or dampens processes that change a state of variable, e.g. the earth's global temperature. Positive feedback makes the temperature change larger than it would have been without the feedback, amplifying the temp change. Negative feedback counteracts some of the external forcing, tending to stabilize the state variable.

How does the ITCZ location change throughout the curse of a year? Explain why

ITCZ does not lie along the geographical equator but along the meteorological (or thermal) equator. In July, it is located just above the geographical equator and in January, a bit below the geographical equator.

Explain the basis for the recommendation: it is not recommended to exercise, especially in the afternoon. If you want to exercise anyway do it early in the morning or late in the evening. When ozone levels are high.

In the first part of the day there is an increase of NO emissions by cars and accumulation of because of thermal stability and the ROG:s also increases with anthropogenic activities during the day. Closer to noon, ROG:s chemical breakdown is involved in the ozone production, and the ozone concentration increases. The photochemical pollution peak in the end of the afternoon and later on there's a decrease in sunlight and the formatin of ozone basically stops.

What can you say about the lapse rate in the stratosphere? What consequence does that have for pollutants injected into this atmospheric layer?

In the stratosphere we have high stability due to very little vertical mixing and long residence time of gas molecules and aerosols entering the stratosphere. Pollutants emitted here will have a bad consequence since the residence tome is long. However, methane and nitrous oxide will be broken down here through photo-dissociation. 90% of all ozone molecules are in the stratosphere but the ozone is also broken down by nitrous oxide.

How does the changes in the land carbon cycle in turn influence back on atmospheric CO2 levels?

i. Higher rates of fires and drier wetlands can disrupt the yearly carbon capture cycle of trees converting forests to grasslands. ii. Dryer wetland risk releasing enormous carbon storages to soil reliant on a lack of oxygen to stay there.

Through which mechanisms do higher temperatures and atmospheric CO2 levels influence the land carbon reservoirs and flows

i. Photosynthesis rates (per area and time) increase temperature, sunlight, water and nutrients availability and atmospheric CO2 levels. ii. Increased temperature leads to faster growth in vegetation but also more forest fires and dryer climate, draining wetlands and speeding up decomposition. iii. Increase in CO2 concentration leads to faster growth in vegetation.

Describe the feedback mechanisms on land carbon storage.

i. The increased growth rate ledas to more carbon capture during the summer season by forests as long as there is enough rainfall. ii. The higher temperature have a negative effect on precipitation and thereby cause forest fires that release large amounts of carbon and favor grasslands, thereby converting forests to less carbon dense grasslands. It also dries up wetlands storing carbon by preventing decomposition. Decay rates increase exponentially with temperature even though the understanding of the mechanisms of how soil decay rates change with temperature is very poorly understood.

What are the two key causes of sea level rise that are linked to global warming

i. The sea level rise is caused by thermal expansion of sea water. The density of sea water decreased with increasing temperature. As the temperature of the water increases, it expands and we have seal level rise. The majority of sea water is in the so called deep ocean and the dynamics of thermal expansion follows approximately the temp increase in the deep ocean and not primarily the surface temperature. ii. The melting of ice caps and sheets. These are very large uncertainties regarding future sea level rise, bur a speculative lon-term sea level rise can be estimated from paleoclimatic information.

What are the two main atmospheric components? Give the corresponding percentage, by volume of dry air.

Nitrogen (78%) oxygen (21%)

Describe how the ice and snow albedo feedback determines the value of climate sensitivity.

An increase in surface temperature leads to melting of both snow and sea ice. This reduces the surface albedo which in turn increases the surface absorption of solar radiation. this feedback continues until a new equilibrium has been reached.

Does the position of the upward branch in the Hadley cell move with time and what consequences does this upward movement of air have on the local climate.

Depending on the earth's rotation, different positions gain the most solar energy and thereby changes the position of the equator. When warm air travels upward and meets cold air, it condenses and creates clouds which leads to high precipitation and rainforests.

What is the difference between fast and slow feedbacks? Name a few exampels

Fast feedbacks are included in the climate sensitivity, i.e. baked into the number. - water vapor (positive) - clouds (positive and negative) - snow and sea ice (positive) - lapse rate (negative) Slow feedbacks - vegetation changes - biochemical changes - permafrost - ice sheets

Describe the ocean cycle

First gaseous CO2 has to dissolve into the sea. The dissolved inorganic carbon, DIC, can reside in three fully oxidised forms. They form through carbonate buffering. The surface water and deep has to mix through downward diffusion. The next step is calcium carbonate buffering which also stabilize the ocean pH.

Give an example of a weather related process that influence one of the ocean structure properties over the globe and/or over time.

Frequent wind patterns move he surface water and create currents.

The uneven solar heating of the Earth's surface is responsible for the wind circulation on a global scale. Winds are initiated by the pressure gradient force, due to thermal differences. They are then deflected by the Coriolis force. Explain why lower latitudes receive more solar energy than higher latitudes.

From the Equator to the poles, the Sun rays meet the Earth at smaller and smaller angles; The light gets spread over larger and larger surface areas. Tropical latitudes receive much more solar energy per unit area than polar regions.

Describe how cloud feedback determines the value of climate sensitivity.

High-altitude clouds typically transmit much solar radiation, while the opposite holds for low-altitude clouds. Low-altitude clouds have a relatively high temp while high-altitude clouds have a relatively low temp. More high clouds generate positive feedback in the form on increase in the new downward radiative flux at the top of the atmosphere. More low clouds, on the other hand, is negative feedback in the form of decrease in the new downward radiative flux at the top of the atmosphere. The existing models point toward an increase in altitude of high clouds and a decreasing number of low clouds with a brightening of low altitude clouds.

Define the concept of a black body

It is a theoretical body that absorbs all incoming electromagnetic radiation, reflecting or transmitting none, and emits electromagnetic radiation called black body radiation. The radiation emitted by a black body depends only on its temperature.

Explain the meaning of "geostrophic approximation"

It is the sum of Coriolis force and he pressure gradient force to foresee the direction of the wind.

Describe why some types of clouds tends to cool the surface on the earth while others tend to warm it.

Low altitude clouds contribute to cooling of the surface. High altitude clouds contribute to warming of the surface. More vapor near the surface -> thicker clouds: higher albedo so they reflect more solar energy and thus surface will be colder (negative feedback). Less vapor far from the sun to reach earth's surface and thus they have a warming effect (positive feedback)

Explain why the CO2 methane-equivalent emissions is so sensitive to the choice of time horizon and metric choice

Methane is rather sensitive to the choice of time horizon: in the first years it's a powerful GHG, however with time it gets weaker compared to CO2. As a consequence, it is observed that for GWP and GTP-20 annual equivalent emissions for methane are much higher than in the 100 year horizon.

Sketch and describe the verival structure of the ocean.

Mixed/surface layer is stirred by the wind, so constant temp and salinity vary generally between 10-200 m in depth. Depth and temp depend on heath flux and turbulence. Thermocline is rapidly decreasing in temperature til the deep ocean. Deep ocean is cold and very deep. Has a homogenous temperature and makes up most of the oecan.

Describe the important features of the ozone layer and planetary boundary layer (PBL)

Ozone layer - stong O3 concentration increase around 25km (stratosphere) - absorbs solar UV incoming radiation via photochemical reactions. - Ozone hole: due to release of halogen compounds by humans - main heat source in the stratosphere PBL - lower part of the troposphere, where the surface strongly influence temperature, moisture and wind. - characteristics: turbulence and vertical mixing varying weight often topped by an inversion layer (r>0) -> less exchange with the free atmosphere

What is meant by parameterization in atmospheric modelling?

Parametrization in a weather or climate model in the context of numerical weather prediction is a method of replacing processess that are too small-scale or complex to be physically represented in the. model by a simplified process. This can be contrasted with other processess - e.g. large-scale flow of the atmosphere - that are are explicitly resolved within the models. Associated with these parameterizations are various parameters used in the simplified processes. Examples include the descent rate of raindrops, convective clouds, simplifications of the atmospheric radiative transfer on the basis of atmospheric radiative transfer codes, and cloud microphysics. Radiative parameterizations are important to both atmospheric and oceanic modeling alike. Atmospheric emissions from different sources within individual grid boxed also need to be parameterized to determine their impact on air quality.

Why and how does ruminants produce methane in their feed digestion? Describe the mechanisms behind the emissions. Make drawing(s) to illustrate your explanations.

Ruminants have anoxic organ: ruman. The rumen can digest cellulose and the microbes produce methane, which is exhaled. 5-8% of the eaten food is transformed to methane. Hydrolysis and fermentation by anaerobic bacteria which gain energy from partial oxidation of carbon in organic matter to fatty acids H2 and CO2. Degradation of fatty acids, H2 and CO2 by "archaea" leads to anoxic energy gain through

Do a rough estimate of the TCRE and make a sketch of the global mean surface temperature as a function of the cumulative CO2 emissions, based on the impulse response in the figure.

TCRE is the ratio of the globally averaged surface temperature change per unit of carbon dioxide emitted. The average in 300 years can be approximated to 0,55 mK/GtCO2

Describe the change in carbonate buffer chemistry in seawater in response to addition of carbon dioxide. Why does adding carbon dioxide make seawater more acidic?

The inorganic carbon in the oceans comes from their air-sea gas exchange. CO2 exists in dissolved form in seawater. At equilibrium, the amount dissolved gas is proportional to its atmospheric partial pressure. Divergences from equilibrium drives gas exchange. An increase in atmospheric CO2-level increases the amount of carbon in the ocean. The solubility constant K0 decreases with temperature, so an increase in water temperature decreases ocean carbon and increases atmospheric carbon.

What is the intertropical convergence zone (ITCZ)? What can you say about the wind and the typical weather in this region?

The ITCZ is an area close to the equator where the northeast and southeast trade winds converge. This is alos where the maximum solar heating is. The ITCZ is characterized by weak an erratic horizontal winds and intense convective activity, that appears as a persistent band of clouds visible from space.

Explain what forces act on air parcel at rest, and what the hydrostatic balance corresponds to

The amount of air parcel above creates a pressure which decreases with altitude. Hydrostatic balance is the condition of a fluid at rest. This occurs when external forces such as gravity are.

Define the lapse rate. How is it calculated? Explain what important information it gives about an atmospheric layer?

The lapse rate is the rate of decrease of temp with height and is defined as: r<0 high stability r>0 instability The average lapse rate in the troposphere is 6,5 K/km

Describe and state the chemical reactions of the two important mechanisms through which NOx is generated in combustion.

Thermal NOx is formde under very high temperatures (>1700°C) Air O2 + Air N2 = 2NO The higher flame temperature, retention time and O2 availability the more thermal NOx. Fuel NOx is formed when the fuel contains a lot of nitrogen. Is positively correlated with fuel nitrogen content, temperature and O2 availability.

Why is the air moving dry downwards above the 30th parallels and what consequences do these downward branches have on the local climate?

When the air reaches the atmosphere it gets colder and starts to travel downwards again. Having lost most of its water vapor to condensation and precipitation in the downward branch of the hadley cell circulation, the descending air is dry, hence creating a dry climate (desserts)

What are the mid-latitude westerlies blowing eastwards?

When wind travels down at 30° it creates a high pressure that wants to move north towards the low pressure at 60°. When the wind is constant, it is affected by the coriolis effect and on the northern hemisphere, it moves the forces to the right. Thus the wind traveling north is changed to move to the east. The pressure gradient force is the principal driving force producing horizontal airflow, the Coriolis effect does not initiate the winds, but once the air is moving, it influences its direction.

What are the main properties that determine the structure of the ocean?

Wind-driven circulation affect mostly the mixed layer. Density, the dominant one, affect mostly deeper part of the ocean (Thermocline and halocline)

Why is ozone an important greenhouse gas and how does it interact with radiation. What effect does it have on the energy budget of the earths surface?

With ozone the earth receives less radiation from the sun. Without it harmful UV light would reach the surface. Ozone absorbs wavelengths shorter than 245 nm and weakly from 250-750 nm. The stratospheric ozone allows little UV-C, some UV-B and almost all UV-A radiation to reach the troposphere. Ozone not only absorbs shortwave radiation but it also absorbs some of the long wave radiation emitted from the earth, and then also contributing to global warming.

Define the term "aerosol". Give at least four examples of different kinds of aerosols and explain what their sources can be.

aerosols= fine solid particles or liquid droplets suspended in the air. The aerosols come from both natural and anthropogenic sources. If the aerosols are composed of water, we call them hydrometeors. Natural aerosols: fog or mist, dust, forst exudates, geyser steam. Anthropogenic aerosols: particulate air pollutants and smoke.

What proportion of the ozone column is located in the troposphere and statosphere?

10% in the troposphere 90% in the stratosphere around 25 km (O3 mixing ration is 200 times higher in the atmosphere)

What are the spectral ranges?

10-400 nm UV 400-700 nm visible 700-10^6 nm infrared

Explain the mechanisms by which weathering of rocks control atmospheric CO2 levels on time scales of million years.

1. Chemical weathering of rocks is a pathway for carbon to exit the biosphere and return to the solid earth. 2. In steady-state, the weathering carbon sink is balanced by the degassing source (≈0,1 Pg c/yr) 3. Dependent on rainfall and therefore dependent on temperature. 4. Response time scales of the thermostat is several 100 000 years.

How is radiative forcing defined?

1. Definition: Radiative forcing is a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the troposphere and is an index of the importance of the factor as a potential climate change mechanism.

What are the two main components of the global ocean circulation?

1. Wind - dominates the surface currents (to 500m) 2. Thermocline circulation - the ocean conveyor belt - circulation in deeper parts of ocean - density differences

Ozone is considered as a pollutant in the troposphere, while its presence in the stratosphere is an essential protection for life on Earth. Explain what is the harmful impact of tropospheric O3 and what is the beneficial role of stratospheric O3.

About 90% of all ozone molecules in the atmosphere reside in the stratosphere. The ozone layer in the stratosphere protects the earth from harmful UV radiation, compared to the ozone in the troposphere which is harmful to both humans and ecosystems. In the troposphere, near ground-level, ozone molecules contribute to trapping heat and climate change. A small amount of ozone does occur naturally at ground level. Plants and soil release some. Some migrates down from the stratosphere. But neither of these sources contributes enough ozone to be considered a threat to the health of humans or the environment. Most of the ozone that us found near the ground comes from vehicle exhaust and emissions from factories, power plants and refineries. When it's inhaled, ozone can damage lung tissue. Ozone is harmful to all types of cells. Ozone also damages materials like rubber, textile dyes, fibers, and certain paints. These materials can be weakened or degraded by exposure to ozone. Some elastic materials can become brittle and crack, while plaints and fabric dyes may fade more quickly.

Why and how does food production cause nitrate emissions

Agriculture Leakage comes from agriculture. NO3- is the most stable form of nitrogen. It has a higher water solubility and nitrates negative charge makes it very mobile in soils. Large amounts of nitrate cannot be stores in soil ans the excess is easily lost from the soil by leaking to groundwater. Annual crops necessitate long periods of bare soil, with no growing crops and hence no uptake of soil nitrate by plants. Mineralization of organic nitrogen in soils i.e. conversion of organic nitrogen to nitrate, occurs as long as the temperature is above 0°C. Hence the period with no plant uptake and continuing mineralization causes an excess of nitrate in the soul and is emitted by leaking. Food production Food production leaks a lot of ammonia (NH3) which has high solubility in water. NH+ is released through fertilization and manure. These quickly turn into nitrate when exposed to O2. Can be reduced by mixing well with the soil as the NH4+ adheres to the soil particles. Organic nitrogen is also quickly converted to nitrate when exposed to O2.

How is natural ozone formed in the stratosphere and lost in the stratosphere and why can't that occur in the troposphere

At and altitude of 25 km sufficient energetic UV-radiation encounters sufficient O2 density for ozone creations, absorbing large amount of high energy radiation preventing it from reaching the troposphere, thus making the radiation energy in the troposphere to low to produce any significant amount of tropospheric ozone.

Explain the mechanisms of the "organic carbon pump" in the ocean. Make a drawing to illustrate your explanations. Also, explain how this pump influence the CO2 concentrations in the ocean and the atmosphere, respectively.

Carbon increases with depth. "soft tissues pump" contributes to lower CO2-concentrations in the surface ocean. The carbonate pump contributes to higher CO2-concentrations in the surface ocean but adds to DIC downward export.

One important characteristic of a soil is its CEC value. How is CEC defined?

Cation exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmolc/kg. It is as very important soil property influencing soil structure stability, nutrient availability, soil pH and the soil's reaction to fertilizers and other ameliorates.

Characterize briefly the importance of soil colloids for a soil's chemical and biological properties.

Clays and organic matter impart to soils some colloidal properties including retention of ions and molecules, water and gas adsorption, and shrinking and swelling, since colloidal particles react strongly with fluids due to their surface area.

Explain what the figure shows

For what wavelength O2 and O3 (mostly O3) are absorbing and what fraction of the UV radiation is absorbed (0,1-0,3 micrometer) and a fraction of GHG are absorbed (9 micrometers) Wavelength between 0,1 to 0,3 is an ozone cloud used as a protective layer against energetic UV radiation. Wavelength between 9 to 10 explains radicals of greenhouse gases.

What are the maxima due to in the vertical template of the atmosphere?

Troposphere: Earth's surface is the major source of heat. Stratosphere: Direct heat surface for the stratosphere is the sun. Mesosphere: the heat source is the stratosphere below. Thermosphere: density of the molecules is really low since so little energy is transferred the air feels very cold. Absorbs energy from the sun.

Explain the relation (<,≈ or ) between average residence time and average age for carbon in the soils.

Residence time < age: examples include water in a lake with the inlet and outlet on opposite sides and radioactive material introduced high in the stratosphere by a nuclear bomb test and filtering down to the troposphere. Residence time ≈ age: examples include radioactive decay and frist order chemical reactions (where the reaction rate is proportional to the amount of reactant). Residence time > age: most of the particles entering the control volume pass through quickly, but most of the particles contained in the control volume pass through slowly. Examples include water in a lake with the inlet and outlet that are close together and water vapor rising from the ocean surface which for the most part returns quickly to the ocean, while for the rest is retain in the atmosphere and returns much later in the form of rain.

How do you explain that the sky is blue, while the clouds are white? What is the physical process behind this difference?

Scattering: Physical process that deviates radiation from its straight trajectory due to localized non-uniformities in the medium. Why is the sky blue? the shortest wavelength corresponds to the blue color and when scattering occurs it is more efficient to scatter short wavelengths than long. Clouds, water droplets scatter all colors equally which gives the white color.

Is ground level O3 a primary or secondary air pollutant?

Secondary air pollutant, these are chemically formed in the atmosphere from precursor pollutants, eg. O3, NO2 etc. (primary air pollutants are directly emitted into the atmosphere, e.g. NOx, particulate matter, CH4 etc.)

What consequences does the mid-latitude westerlies blowing eastward have on the weather in Gothenburg?

Since Gothenburg is on the 57th we usually have west winds. The fact that the Atlantic ocean is west of Gothenburg means that we will have relatively high humidity.

Describe two other problematic effects related to high levels of ozone in the troposphere.

Smog and toxicity. Photochemical smog is caused by fuel burning from nitrogen oxides, fuel extraction and industry processes from volatile organic compounds. This can lead to health issues such as decreased lung function, deadly heart and lung diseases.

Why are elevated ozone levels much more common in the summer?

Smog formation does not only require important pollutant emissions, but alos favorable weather conditions. The concentrations of pollutants are affected by wind, temperature, vertical thermal profile (air stability), cloud cover, precipitation and humidity. Under calm air conditions, pollutants cannot disperse and get trapped near the surface. Such conditions enhance near-surface pollution build-up. ON the contrary, when strong turbulent winds blow, pollutants disperse quickly, resulting in lower concentrations. Moreover, rainfalls wash aerosols out of the atmosphere and can also dissolve gaseous pollutants resulting in cleaner air. Hence the season have a a strong influence on ground-level ozone production.

Describe sulfurous smog and it's favorable weather conditions

Smog is a word for the mix of smoke and fog that reduces the visibility. Sulfurous smog looks almost like smoke and is make from primary pollutants such as SOx from fossil fuel burning that are accumulated due to stagnant weather conditions. The smog is strongly influenced by meteorological conditions. It is most common in moderate climate and colder seasons, because of its origin. Lack of wind facilitates the formation. Thermal inversion makes the formation even easier, it causes rise of temperatures in the higher layers of the atmosphere which makes it impossible for the air masses to mix.

What are "soil colloids"? Specify their typical properties.

Soil collioids are the finer fractions of the soil (clay and organic matter), being also considered of their large surface area and the chemical structure of the final materials involved.

What do we call an atmospheric window?

Spectra range where the atmosphere is transparent, optically thin, and radiation can be transmitted without distortion or absorption.

Explain how anthropogenic activities can contribute to the rapid destruction of the stratospheric ozone layer. Give a few examples of ozone depleting substances and describe the principle of O3 catalytic destruction cycles.

The anthropogenic CFCs can destroy stratospheric ozone. he compounds that play the most important role in reducing stratospheric ozone are CFCs. These are gases formed synthetically such as replacing on or more chlorine atoms with flourine in carbon tetrachloride. CFCs are a subset of chlorocarbons, which are compounds containing carbon and chlorine. HCFC are another subset of chlorocarbons and is similar to HCFCs has at least one hydrogen atom. The result of this sequence is that one molecule of ozone is destroyed, but neither NO nor NO2 is lost. This sequence is called the catalytic ozone destruction cycle because the species causing the ozone loss is recycled.

Describe the carbonate system

The carbonate system is based on multiple reaction which can be summarized as: CO2 + H20 = H2CO3 This is a buffer system which keeps the pH stable short terim Is based on the total dissolved inorganic carbon, DIC, and the total alkalinity, Alk. The system is the reason to why so much CO2 can dissolve in the ocean. It is approximately 80 times more compared to if it only was gas exchange that dissolved CO2 in the ocean. The pH regulation is important to ensure that shell formation can continue.

Which are the two most important components that gives a soil a high CEC?

The clay mineral and organic matter components of soil have negatively charged sites on their surfaces which adsorb and hold positively charged ions by electrostatic force. This electrical charge is critical to the supply of nutrients to plants because many nutrients exist as cations. In general terms, soils with large quantities of charge are more fertile because they retain more cations however productive crops and pastures can be grown on low CEC soils.

What is the Coriolis force? Explain what it is due to, on which kind of bodies it acts, how it changes with latitude and how it influences the wind, in each hemisphere.

The coriolis force is a fudge factor, allowing us to ignore, in the equations of motion, the fact that the earth is rotating. The Coriolis force acts in the horizontal plane only and goes 90 degrees to the right of the velocity of a moving air particle in the northern hemisphere and 90 degrees to the left in the southern hemisphere. The Coriolis force starts out at zen at the equator and increase as you travel closer to the poles, as the radius from you to the earth's axis decrease.

Which factors determine carbon levels in mineral (normal) soils? Describe four important factors and explain how they influence soil carbon levels. Make drawing(s) to illustrate your explanations.

The decay rate is proportional to soil c content. Soil temperature; with higher temperature there is higher decay of soil carbon compared to cold climate. Vegetation type: depending on type of vegetation different plants absorb and transfer more or less carbon in the soil. Human management of land; input per hectare to the soil from agriculture crops is typically lower than that of forests and native-vegetation land. Also, shorter cultivation periods of agriculture crops reduce land carbon storage (because there's less NPP production) Photosynthesis; the more photosynthesis the more generated carbon.

Why is the air moving upwards in the equatorial region (upward branch of the Hadley cell)

The hadley cell is convection cell in the tropics. Greater heat absorption leads to low pressure and higher surface temperatures, warmer air travels upwards. The lower latitudes receive more solar energy than polar regions

Is the net of cloud feedback likely to be positive or negative?

The impact of thick clouds is negative and in general there are more thick clouds than thin. Therefore the ner impact should be negative. However some prospect believe that we will have more thinner and higher-altitude clouds in the future.

Define the natural greenhouse effect. How large is it? Which are the two major gases contributing to this effect?

The most important greenhouse gas is H2O, followed by CO2. Given a fixed albedo of the earth, the natural greenhouse effect causes the earth to be about 33 K warmer than what it would had been without it. The greenhouse effect can be understood by application of energy balance calculations and stefan boltzmann's law. The strength of the greenhouse effect depends on E of the atmosphere and the difference between the temp earth and temp atmosphere.

Explain why trace gases play a very important role in the atmospheric system? Give at least three example reasons

The most important trace gases found in Earth's atmosphere are the so-called greenhouse gases. These trace gases are called GHG because they help to keep earth warm by absorbing light from the sun. Whilst ozone behaves like a GHG in the troposphere, in the stratosphere where its abundance is most significant within the ozone later, it helås to filter out the incoming UV radiation from the sun, protecting life on earth from its harmful effects. CO2 is important for photosynthesis, however the anthropogenic amount has drastically increased and is now contributing to the greenhouse effect.

Why does the calculation of the photostationary-state hypothesis not give an accurate estimate of the O3 concentration under polluted urban air conditions.

The pollutants in urban air are involved in several chemical reactions that converts more NO to NO2, increasing the NO2/NO ration and thus ozone, compared with the photostationary-state relationship.

Define the residence time and age, respectively, used when dealing with materials fluxes in the environment.

The residence time is the time spent in a reservoir by and individual atom or molecule. Different atoms and molecules will have different residence times in a given reservoir. The age of an atom or molecule is the time it has been in the reservoir up till now.

Describe how water vapor feedbacks determines the value of climate sensitivity

The saturation vapor pressure increases with temperature and the increase in atmospheric water vapor is estimated to about 7%/K. When the surface temperature increases, the specific humidity also does. This further increases the surface temperature, and the feedback continues until a new equilibrium is reached.

Describe the important features of the atmospheric layers.

Troposphere (0-15 km) - Most of the mass of the atmosphere (75-80%) - almost all weather occurs here - unstable layer dure to importent vertical mixing - planetary boundary layer Stratosphere (15-50 km) - stabile due to inhibition of vertical motion - long residence times of gas molecules or aerosols entering the stratosphere. - strong influence of waves and tides - polar stratospheric clouds. Mesosphere (50-90 km) - considered edge of space - high concentration of iron and other metal atoms (meteor disintegration) - polar mesospheric clouds - high energetic solar particles interact with the molecules in the mesosphere, important for solar influence on climate. Thermosphere (90-700 km) - very low density and pressure - mainly made of atoms and ions - strong influence of solar activity - where aurorae occur - considered as outer space