Module 1 Flashcards
What is a system?
Any ordered, interrelated set of ‘things’ (a lake in a watershed, the earth and the sun) linked by flow of energy or matter. The system must be conceptually separated from the surrounding environment outside the system. A system can have subsystems.
What are the 4 attributes of environmental systems?
- Function (structure and fluxes)
- Scale
- Feedbacks
- Equilibrium states
What is an open system?
Inputs of energy and matter flow into the system, and outputs of energy and matter flow from the system. Inputs of matter and energy undergo conversion and are stored or released as the system operates.
For example: earth and solar energy entering, heat energy leaving.
What is a closed system?
A system that is shut off from the surrounding environment. Closed system links the input and outputs.
Example: water cycle
What is an environmental system budget?
What comes into the system and what leaves the system.
Inputs - Outputs = change in storage
- if the inputs are larger than the outputs, the change in storage increases.
- if the inputs are smaller than the outputs, the storage decreases.
What are the functions of a forest?
- changing the climate
- keeping the surface of the soil cool
- nutrient storage, stored in the canopy
- biomass that contains carbon
- exchange of gases with the atmosphere
Explain a leaf during the day vs night as an open system.
Day: photosynthesis dominant
- Sunlight as an energy input and water, nutrients and CO2 as energy inputs.
- photosynthetic process converts the inputs to stored chemical energy in the form of sugars (carbohydrates).
- releases oxygen as an output.
Night: no photosynthesis = respiration dominant
- input: mainly O2 from atmosphere but also H2O, minerals and nutrients.
- carbon is converted in CO2.
- output: water lost through transpiration and leaf loses heat because of cool off.
Controls on leaf CO2 exchange:
- nutrient (nitrogen)
- temperature
- light
- nitrogen: linear (+ nitrogen = + chlorophyll)
- temperature: not linear, but max value at which rate can rise, then decline.
- light: non-linear (dependant on light)
Define negative and positive feedback.
Negative: feedback information discourages change in the system. Further production of the feedback opposes system changes and leads to stability.
Positive: feedback information encourages change in the system. Further production of positive feedback causes system change.
Define steady state equilibrium.
When the rates of outputs and inputs in the system are equal and the amounts of energy and matter in storage within the system are constant. Negative feedbacks dominate.
Define dynamic equilibrium.
Steady state equilibrium that demonstrates change overtime. Positive feedbacks dominate is driven by unstable equilibrium.
Radiation and temperature.
All bodies that possess energy emit ‘radiation.’ Temperature is a measure of how much internal energy a body has.
The higher the temperature,
- the more radiation is emitted
- the shorter the wavelengths emitted
Define solar constant.
Average value of insolation when earth is at its average distance from the sun = 1370/m^2. The constant varie due to sun spot cycles.
What are the reasons for variation of insolation with time and space.
- Earth’s revolution.
- Earth’s rotation.
- Tilt of the Earth’s axis.
- Earth’s Sphericity.
Explain insolation on a curved surface.
Differences in the angles at which solar rays meet the surface at each latitude results in an uneven distribution of insolation and heat.
- full radiation received at the equator (sub polar point).
- more concentrated, smaller areas to cover near the equator receive more insolation.
- more diffuse, larger areas covered at the tropics receive less insolation.
Define net radiation.
The balance between incoming short-wave energy from the sun and all outgoing radiation from the earth and the atmosphere.
Energy inputs minus energy outputs.
Define seasonality.
Refers to both to the seasonal variation of the sun’s position above the horizon and to changing day lengths during the year. Seasonal variations are a response to changes in the sun’s altitude or the angle between the horizon and the sun. These are caused by the variations of solar radiation (4).
Explain air pressure and the temperature of composition of atmosphere.
Air pressure changes throughout the atmospheric profile - divided by the Earth’s layers.
- dense collection of gases towards the surface, less dense as we go higher.
- with increasing altitude, density and pressure decrease.
- temperature decreases as we go upwards towards new compositions of the earth. At the certain point, it starts to increase due to the ozone layer capturing solar radiation.
Define transmission, atmospheric scattering/reflection, atmospheric absorption.
- Passage of parts of shortwave and long wave radiation through the atmosphere (atmosphere is ‘transparent’ to these components).
- Atmosphere interacts with insolation through processes of scattering, a redirection of radiation through refraction and reflection from particles (aerosols and water droplets).
- Some of the short short and long wave radiation is absorbed (and heats up) some constituents in the atmosphere.
Explain the ‘Greenhouse’ Effect.
- without GHGs, the earth’s temperature would be around 255K (if earth was a black body).
- average surface temperature of the earth is 288K.
- the difference between the two temperature is 33 degrees: magnitude of the greenhouse effect.
- increased greenhouse effect contributes to global warming and climate change.
Explain the ozone layer.
- Ozone absorbs the shorter wavelengths of UV radiation.
- UV energy is converted to heat energy - it filters the Sun’s harmful rays. When it absorbs solar radiation, the ozone layer warms up.
What causes the depletion of the ozone layer?
- CFC production - when chlorine reacts with a one and depletes the ozone layer.
- Strong, stable and cold polar vortex and very cold temperatures in the stratosphere (ozone hole).
Explain how ozone warms and cools the earth.
Warms:
- absorbs UV radiation = heats the stratosphere.
- absorbs IR radiation emitted by earth’s surface = traps heat in the troposphere.
Cooling:
- major ozone losses observed in lower stratosphere due to CFCs have a cooling effect.
- the absorption of radiation is decreased by depletion of ozone - the radiation is reflected by albedo effect = cooling.
- ozone is cooling when it is lost in the stratosphere.
How does the Montreal Protocol protect the carbon sink?
Increased UV radiation decreases NPP - it is destroying the photosynthetic capacity of plants = decrease in CO2 uptake.
With no Protocol, it would lead to higher atmospheric concentrations of CO2 and contribute to accelerated global warming.
INDIRECT effect of reduced O3 depletion.