Environmental Science lecture notes - including most end of year questions

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Environmental Science
Luc Bernier

Environmental Science lecture notes Environmental science first lecture: -water vapor is at the center of the atmosphere -dark grey areas on water vapor scale means its relatively dry compared to lighter areas -higher co2 ppm per million molecules in the atmosphere… rapid increase since industrial revolution atmospheric aerosols influence air temperature, play a role in cloud formation, are generated by human activities and natural processes, include sea salt crystals We find Ozone at ground level cause of cars' fumes.. Found in smog. It is bad on the ground. QUESTIONS: 1. The thermosphere has extremely high temperature, but a person exposed to it would rapidly freeze. Explain this apparent contradiction. -not enough molecules close to each other to transmit the heat to your body plus the pressure is so low. 2. What climate-change processes might you expect to witness during your time? Which ones do you think take too long for you to experience? -Seasons. Global warming/ice age Environmental Science lecture 2 -air is denser near the Earth's surface atmospheric pressure is force exerted by air molecules per unit area Ideal Gas Law states: --> slide 3 p=pRT temperature=constant X pressure -air pressure decreases with altitude -air at a higher altitude less dense -> less oxygen -altitudes above 3000 meters can cause mountain sickness Questions: Pressurized cans of shaving cream say not to expose to excessive heat. What might happen if it is and will this potential problem last throughout the product life. A standard pressure of 1,013.2 hPa is also known as one atmosphere (1 ATM). Look at the next figure and determine at approximately what levels you would record a pressure of 0.5 ATM and 0.1 ATM. Lecture slides 4: Solar luminosity was much less 4.6 billion years ago when Earth formed. The Earth was colder than now. To find the intensity of the radiation: Stefan-Boltzman equation: E=oT^4 A blackbody is a body that is perfectly efficient at emitting radiation For graybodies, Stefan-Boltzmann equation becomes I=eoT^4 Wein's Law: A=2897/T The impact on Earth's temperature if scattering in the atmosphere increase would depend on which type of scattering. But usually colder. If cloud cover increased, the Earth's temperature would be Net Radiation= incoming radiation-outgoing radiation Poleward heat transport: Surplus energy moves toward poles (deficit regions) Poleward heat transport is a driving force of climate Warming is occurring due to the presence of greenhouse gases. Incoming solar energy is equaled to the outgoing IR energy. Greenhouse effect keeps the Earth warm. Without it the Earth's temperature would be ~ -15 degrees celsius Energy absorbed by Earth - Energy absorbed at the surface = Energy recycled within the Earth's system Questions: Would you expect both the Northern and Southern hemisphere to have same average albedo/ What factors might cause the two hemispheres to reflect different percentages of insolation back to space? -->No they won't have the same average altitude because southern him sphere has more water than land mass, and northern hemisphere has more land so more snow will increase average albedo. Which would have the greatest effect on the Earth's greenhouse effect: Removing all of the CO2 from the atmosphere or removing all of the water vapour? Explain why you chose your answer. --> Environmental Science Lecture 3 Lecture 5 Sub-solar point - at noon, the sun will be directly over it -summer in the southern hemisphere is associated with the sub solar point at 23.5 degrees South. -an average rate of 55W/m^2 in insolation can be observed at 90 degrees South, at the December Solstice. -an average rate of 440W/m^2 in insolation can be observed at 0 Degrees, at the March Equinox -the maximum temperature occurs in mid-late afternoon even though the the amount of time it takes to reradiate the solar radiation -temperature is more inconsistent the further from the equator -equatorial zone is associated with rain forests -grasslands are associated with the midlatitude zone -If the Earth was not tilted, the Earth's radiation budget would have a greater loss of energy at high latitudes -coastal locations have lower temperature ranges than locations inland because it takes a lot more energy to heat up a body of water than land -wind mixes the warm water with the cold water -greater loss of latent heat with a body of water Continentality-effect of an inland location that favours greater temperature extremes -What factors influence local temperatures--> surface type, latitude, elevation -The surface type contributes the most to maintaining temperatures at a given location higher than nearby areas (asphalt holds heat more than vegetation, farmers fields etc.) -there will be a higher range of temperature year round the further the area is from water/the higher the latitude -the Wind-Chill index is the "feel" of temperature under cold conditions QUESTIONS: An orchard farmers hears a weather forecast for overnight low temperatures to hover just above freezing point of 0 Degress Celsius, but with wind chill temperatures expected to drop significantly lower. Will the wind chill increase the possibility of frost damage? Why or why not? ANSWER: Suppose that the Earth's axis were tilted at 40 degrees to the plane of the ecliptic, instead of 23.5 degrees. How would the seasons change in Hamilton? what would be the global effect of the change? ANSWER: The summer would be hotter, winter would be colder. The seasons would be even more extreme. Lecture 6 -Humidity is the amount of water vapour in the air. -Specific Humidity (SH) is the actual quantity of water vapour in air -SH=mass of water vapour (g)/mass of total air (kg) -Saturation Specific Humidity is the maximum amount of H2Ov (i.e. SH) that an air parcel can contain at any given time based on its temperature -Saturation is achieved when the density of gas cannot be increased above a certain level - change of phase once limit is reached -Dew Point - Temperature at which air, when cooled, becomes saturated -If two air parcels have the same specific humidity, but different temperatures, they will still have the same dew point -Relative Humidity (RH) = 100 X (SH/saturation SH) -If there temperature rises, and the specific humidity stays the same, the relative humidity will fall QUESTIONS: How can frozen clothes "dry" outside in subfreezing weather? What is taking place? A crowded classroom is filled with students. In what way the presence of the students affect the dew point and relative humidity in the room? Answer: 2. Dew point will be increasing because of more moisture and the more people makes it hotter too. The relative humidity decreases. If the increase in the temperature is far larger than the increase in the dew point, the relative humidity will decrease. Environmental Science Lecture 4 -Pressure (mb) is the same as hPa -Rate of temperature decrease with altitude for a parcel of dry or unsaturated air as it rises: 10 degrees celsius/1,000m -rate of temperature decrease with altitude for a parcel of air saturated with water vapour as it rises: 4-9 Celsius/1,000m -lifting condensation level (LCL): height at which saturation occurs Slide 7 Diagram from bottom to top -Air cools at DALR - Unsaturated -Air becomes saturated - saturated -Air cools at SALR - SALR=MALR -Level of free convection LFC Latent heat released compensates for decrease in temperature Atmospheric stability - no vertical movement occurs -Stability: Air parcel resists upward displacement -Instability: air parcel keeps rising Absolutely stable atmosphere is ELR Spring and Summer, mostly summer (most thunderstorms in summer) Is the stability of the air more likely to change rapidly near the surface or aloft? At what time of day are major changes in the ELR most likely? -->ground Lecture 8 The ELR increases above 10km because the troposphere has been reached Cumulonimbus cloud would be expected to see associated to convection under highly unstable conditions (large difference between MALR and ELR) Orographic uplift is when a cloud hits a mountain and has to rise up and cools down The height of where the base of clouds forms is called the lifting condensation level The air mass starts to warm as it descends the lee side of the mountain at the DALR Questions: Why are advection fogs rare over tropical water? --> it is not the best temperature for advection fogs to form In many regions, the orographic effect causes precipitation to increase with elevation. Can you think of any reason why this might not be true all the way up to the top of Mt Everest? -->By the time the water vapour has been forced to lift along the mountain slope, it has already condensed and formed into clouds and precipitation Environmental science lecture 5 Lecture slide 9 -Precipitation is any form of water that falls from a cloud and reaches the ground - In warm clouds (>0 Celsius): water droplets condense - Constant speed achieved when air resistance = gravity: terminal velocity - In cold clouds (<0 Celsius): ice crystals form & grow -types of precipitation; rain, freezing rain (glaze), snow, sleet -raindrops are not tear- shaped -Bigger than 2mm then its a flattened sphere -smaller than 2mm then its a sphere Snow is distributed throughout North America West: snowfall at higher elevations East: lower temperatures favour snow over rain -Lake effect snow is a strong enhancement of snowfall QUESTIONS: Why is a warm, tropical cumulus cloud more likely to produce precipitation than a cold, stratus cloud? -->there is more moisture that can be held with the cold stratus cloud Both the arctic and the Canadian Prairies have relatively low snow cover. Is the cause for this the same in both regions? --> Lecture slides 10 -Water in all its forms: ~1.4 billion km^3 -Overland and interflow are affected by human development -a water balance represents Hydrological cycle at the local scale Water balance equation: P= (PE-D) + S + or - AST D= PE - AE P= precipitation PE= potential evapotranspiration -moisture demand D= deficit -Moisture shortage S= surplus -oversupply AST: soil moisture storage change -moisture savings AE= actual evapotranspiration -if all demand is satisfied, AE=PE -Deficit occurs when PE cannot be satisfied through; P, soil moisture Under ideal conditions; AE and PE are close -Surplus: When PE is satisfied, and ST is full ACCWL: accumulated potential water loss -water taken from ST when: P< or equal to PE -october to mid december; recharge QUESTIONS: 1. What effect does a large ST have on a location as compared with another location that has the same P and PE totals but a lower ST? 2. How do impervious surfaces such as parking lots impact the water balance terms? --> the actual evaporation is going to be lower, and higher deficits in the summer months; Soil storage. ^ON FINAL EXAM Environmental Science lecture 6 Lecture slides 11 -Wind is air that is moving horizontally relative to Earth's surface. It is caused by unequal heating of the Earth's atmosphere -Winds are generated by differences in pressure drive wide. -Pressure gradient force: difference in pressure between regions -Pressure is mapped by constant height: plot variations in air pressure on a constant elevatio
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