quiz 2 Flashcards
What is the primary driver of Earth’s climate?
Sun
To understand what controls climate we need to consider.. (3)
- How solar energy is absorbed at the earth’s surface
- How energy is exchanged between the earth’s surface and the atmosphere
- How energy is redistributed by the ocean and atmosphere
- In others words, we need to understand the energy budget of the earth
Electromagnetic Radiation
- Visible light is an example
- Receives energy from the sun via electromagnetic (EM) radiation, mostly visible light
- Electromagnetic radiation (EMR) consists of waves of electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy
Electromagnetic Spectrum
(list them)
Raging : Radio (long wavelength)
Martians: Microwave
Invade : Infrared
Venus: Visible
Using : Ultraviolet
X-Ray: X-ray
Guns : Gamma (short wavelength)
equations for the electromagnetic spectrum
- Frequency = c / wavelength
- Wavelength = c / frequency
→ lambda is wavelength, the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave
→ frequency is the time between the arrival of successive peaks
→ c is the symbol for the speed of light
→ energy of light is proportional to frequency
history of science tangent
- Einstein’s Special Theory of Relativity is based on the recognition that the speed of light does not change even when the source of the light moves relative to the observer
- Einstein recognized the huge implications of this. Changed many ideas about the nature of the world
Black-body spectrum
(2 important laws)
- Two important blackbody laws
—-> Wiens law: the higher the temperature the shorter the maximum wavelength emitted
—–>Stefan-Boltzmann Law: the amount of energy emitted (per area) depends on absolute temperature to the 4th power.
scientific model
A representation of a particular phenomena in the world
What are we missing compared to the real world?
Left out reflectivity of the planet and greenhouse gasses
Reflectivity or albedo
Albedo; from Latin albedo ‘whiteness’ , is the fraction of sunlight that is diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to about that reflects all incident radiation)
1815 Eruption of Mount Tambora in Indonesia
“Severe frosts occurred every month; June 7th and 8th snow fell, and it was so cold that crops were cut down. It must be remembered that the granaries of the great west had not then been opened to us by railroad communication, and people were obliged to rely upon their own resources or upon others in their immediate locality” - William G. Atkins
Ice ages
- Earth has had 7 ice age cycles (mostly cold times followed by short warm intervals every 100,000 years) over past 750,000 years
- These are thought to have been driven by cyclic changes in the length of the northern hemisphere summer and amplification by the ice/albedo feedback
What about clouds? Positive or negative feedback?
—> Cumulus and stratus clouds
—-> Cirrus Clouds
Cumulus and stratus clouds
- Low
- Small greenhouse
- Big effect of albedo
→ these clouds cool the climate
Cirrus Clouds
- High
- Large greenhouse effect
- Smaller effect on albedo
→ these clouds warm the climate
Cloud feedback summary
-Most models predict that cloudiness should increase as the climate warms
——->If low clouds increase the most, then the feedback will be negative
——–>If high clouds increase the most, then the feedback will be positive
-The balance of evidence suggests that cloud feedback is negative. However, this is highly uncertain and therefore difficult to model
-This uncertainty is the biggest in predicting the impact of increasing CO2
Atmospheric carbon dioxide
(current day)
We are about 420 ppm (parts per million) of carbon dioxide currently
climate proxies
- In the study of past climates (“paleoclimatology”), climate proxies preserve physical characteristics of the past that stand in for direct meteorological measurements and enable scientists to reconstruct the climatic conditions over a longer fraction of Earth’s history
- Reliable global records of climate only began in the 1880s, and proxies provide the only means for scientists to determine climatic patterns before record-keeping began.
examples of proxies
- Stable isotopes measurements from ice cores
- Growth rates in tree rings
- Species combustion of sub-fossil polled in lake sediment or foraminifera in ocean sediments
- Temperature profiles in boreholes
- Stable isotopes and mineralogy of corals and carbonate speleothems
climate hockey stick
- Temperature with respect to the 1850-1900 mean over the last 2 millennia (blue) and observational estimates ranging from 1850 to 2020 (black). The shaded region contains the 68% confidence interval.
- Compiled studies → prove the climate hockey stick
ice age temperature changes (cause)
Changes in ice age temperatures caused by Earth’s orbit
ice coring drill
- Drill into the ice and will bring up a tube of ice called an “ice core”
- There are bubbles inside the ice core and you can cut/sample the ancient air trapped inside the ice core
why are there violent storms
convection: vertical circulation due to differences in buoyancy
how does natural convection result
Natural convection results from the tendency of most fluids to expand when heated - i.e., to become less dense and to rise as a result of the increased buoyancy
stable atmosphere
air parcels return to their original position after being displaced, and there are calm and predictable weather conditions
neutral atmosphere
a parcel of air lifted vertically will remain at the same temperature and pressure as the surrounding air at each altitude, meaning it experiences no buoyancy and neither rises nor sinks, essentially staying in equilibrium with its environment
