Week 7 Flashcards
1
Q
Earth’s External Energy
A
- Sun drives two vital systems on Earth: Weather, Climate
2
Q
Weather
A
The short-term state of the atmosphere at a given time and place
3
Q
Climate
A
The long-term average weather conditions for a given region of Earth.
4
Q
Earth’s Greenhouse
A
- Most Common: Carbon Dioxide, Methane
5
Q
Venus Greenhouse
A
- 2X Solar Radiation then Earth
- Sun is not only factor since 460 cannot be explained
- CO2 intensifies
6
Q
Earths Impacts
A
- Most go unnoticed
- 100 to 1000 daily
- Huge ones are devastating
7
Q
Layers of the Atmosphere
A
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
8
Q
Troposphere
A
Densest layer, ranging from 8-18km thick
9
Q
Stratosphere
A
Ozone-enriched, reaching up to 50km
10
Q
Mesosphere
A
Asteroids burn up, reaching up to 80km
11
Q
Thermosphere
A
Northern Lights produced by ionization, up to 500-700km
12
Q
Dynamics of the Atmosphere
A
- Weather, the controlling factor is activity of water in the troposphere
- This includes the way water is absorbed or released
- This also involves the way water exists as a solid (ice), liquid, or gas (steam/vapour) on Earth
- As temperature increases, and liquid water is boiled to vapour, energy is absorbed during the reaction
- As temperature decreases, and liquid water is frozen to ice, energy is released during the reaction
13
Q
Latent Heat
A
- The amount of energy released or absorbed by a material during a change of chemical state
- The unit of measurement for Latent Heat is Joules per gram (J/g)
- Most reactions have known Latent Heat values, so predicting whether the absorption or release of Energy will occur
14
Q
Latent Heat and the Atmosphere
A
- The Water Cycle is a rudimentary but accurate depiction of liquid water interacting with the atmosphere to produce storms
15
Q
Convection in the Atmosphere
A
- With water being both evaporated and condensed all over the world, complex cells of air motion form
- The air in the troposphere moves in Convection Cells, Complex air motion is in response to:
- Air Temperature changes
- Air Density changes
- Air Pressure changes
- Density is the most important measure of an airmass, as this determines how it interacts with other airmasses, and is most-dependent on temperature and humidity
16
Q
Atmospheric Density
A
- We measure Atmospheric Density as grams per cubic metre (g/m3)
- As pressure increases, the density increases;
- As temperature increases, the density decreases.
17
Q
Atmospheric density is low when
A
- At high elevation
- At high temperature
- At low air pressure.
- Example: A humid, hot day at a mountain-top
18
Q
Atmospheric density is high when
A
- At low elevation;
- At low temperature;
- At high air pressure.
- Example: A dry, cold day in a low valley
19
Q
Adiabatic Heating and Cooling
A
- If Air Pressure decreases, air density and air temperature must decrease
- The less-orderly atomic arrangement requires more energy to hold the ‘relaxed’ chemical bonds
- If Air Pressure increases, air density and air temperature must increase;
- As density increases, temperature must also increase, releasing heat energy
20
Q
Adiabatic Process
A
- The change in properties without an addition or removal of heat
- As an airmass increases elevation, pressure decreases and it is allowed to expand ‘adiabatically’ (increasing volume)
21
Q
Atmospheric Humidity
A
- Humid air is actually less-dense than dry air
This is because the addition of water vapour to the atmosphere replaces some of the heavier gases - Evaporation happens close to the surface
- From here, water vapour heated by the Sun differentiates upwards through the troposphere, due to the low density
- The water vapour will continue to differentiate upwards until it cools and condensation occurs; when this happens, the density of the water vapour increases, destabilizing the airmass
22
Q
Convection Cells
A
- Because of the spherical shape of the Earth, the Sun does not heat the planet evenly
More heat is received at the equator than at the Earth’s poles - This causes turbulence in the global troposphere, bringing rise to convection currents
- Convection cells force warm air up at the equator and bring cool air down towards the poles
- Factors such as continental landmasses and oceanic currents can affect the ideal global air circulation
23
Q
Coriolis Effect
A
- The force imparted by the spinning Earth on a material, including the flow of air or water
24
Q
Coriolis Effect splits Cells into 3
A
- Hadley Cells
- Ferrel Cells
- Polar Cells
- The effect is based on the angular momentum provided by the Earth’s rotations on-axis and around the Sun
25
Jet Stream Definition
- The strong wind formed by the tumultuous interactions of Hadley and Ferrel Cells; follow yellow lines on the diagram
- Must be 57km/h or more to be jet stream
26
Jet Stream Info
- The Jet Stream produces many strong storms every year
- During periods of prolonged cold, the Polar Jet Stream moves towards the equator
- This often produces strong storms through the atmospheric interaction of cold jet stream air and warm tropical water vapour
- The Subtropical Jet Stream can produce strong storms and also steer their headings
- Sometimes, the winds are too weak to produce an effective jet stream
- To be defined jet stream, winds must exceed 57 km/h
27
Wind
- Air movement driven by variations in atmospheric pressure
- Essentially, wind is the movement of air from high-pressure regions to low-pressure regions of the atmosphere
- The difference in air pressure between the high- and low-pressure regions determines the wind speed
28
High-Pressure Zone
A region of the atmosphere where air pressure and air density are high; air is cooling and sinking.
29
Low-Pressure Zone
A region where air pressure and air density are low; air is heating and rising.
30
Wind Info
- Low-Pressure zones develop an inward spiral motion, relative to ground.
- High-Pressure zones develop an outward spiral motion, relative to ground.
- Wind is also affected as part of the Coriolis Effect
- Generally, a single gust of wind will lose energy over time from friction with the surrounding air and ground
31
Oceans Currents
- Because of Physics, Ocean waters also differentiate based on water temperature and density
- Friction from wind can force warm water down to 100m
- Warm water is heated by the Sun
- The difference in water temperatures and densities cause Ocean Circulation
- Two basic circulation systems:
- Wind-driven surface water circulation
- Density-driven deep water circulation
32
Oceans Density
- Based on salinity
- Salinity is the measure of salts dissolved in water, often expressed in ppt
- Similar to the measurement of humidity in the Troposphere
- As pressure increases with depth, the density of water is forced to increase
- Increasing density forces an increase in temperature
33
North Atlantic Ocean
- Warmest and Saltiest part of Ocean
- Global Ave Temp = 3.51 C
- NAC Ave Temp = 5.08 C
- Global Ave Salt = 34.72 ppt
- NAC Ave Salt = 35.09 ppt
34
Main Thermocline
- The upper 1000m of ocean water of high temperature and salinity
- Everything below the Main Thermocline is called ‘Deep Water’, 77% of world’s oceans
- This depth is picked because it is around 4°C
35
The Deep Water
- 77% of ocean
- Temperatures are colder than 4°C and salinities are in the range of 34.1 – 35.1 ppt
36
The Surface Water
- (23%) highly variable in temperature and salinity
- 25% of surface water is cooled to below 4°C
- When the water is cooled, it sinks under warm water and produces deep ocean currents
37
Ocean Currents and Wind
- Large swirling Gyre currents form under atmospheric convection cells (Hadley and Ferrel), especially near strong Jet Stream winds
38
Gyres
- Gyres help drive ocean circulation as the rotating nature produces a high-point, known as a ‘lens’
- Water at the lens sits about 2m higher than the edges of the gyre
- These giant circulating currents move across all the oceans, and create high- and low-points of varying temperature and salinity
39
Gulf Stream
- A strong current that cuts through gyres, moving warm water from the Gulf of Mexico to the North Atlantic
- The volume of warm air and water moved along the Gulf Stream helps warm Europe by up to ~10°C
40
Thermohaline Circulation
- Thermohaline Circulation describes the exchange of warm and cold waters through the oceans
- In the Atlantic Ocean, the Gulf Stream brings warm water north; this water is cooled by the Arctic temperatures and sinks deeper
- When this cold water flows downward, it travels back south
- This cold water current is known as the North Atlantic Deep Water Current, and carries cold arctic water to the Indian and Pacific Oceans, where it is substantially warmed
