Climate System Basics Flashcards
What are the differences between weather and climate?
Climate is what you expect - weather is what you get. Taking a deeper look at them:
Weather: short-term variations over minutes or days of variables such as temperature, precipitation, humidity, air pressure, cloudiness, radiation, wind and visibility. The predictability is limited to days.
Climate: the average weather which varies slowly over periods of months or longer. It also includes probabilities or frequencies of extreme events.
How big is Earth? How thick is the atmosphere, how deep the ocean?
Earth’s radius is 6.370km, the atmosphere is 480km think and the ocean is 4km deep in average.
What are the components of Earth’s climate system?
the atmosphere: air and clouds above the surface.
The oceans or hydrosphere: oceans cover more than two thirds of Earth’s surface. The major ocean basins are the Pacific, Atlantic, Indian and Southern Ocean.
The cryosphere: sea ice, mountain glaciers and ice sheets on land. Sea ice is frozen sea water floating on the ocean that can be several meters thick. Ice sheets on land are made out of compressed snow and can be several km thick.
Biosphere: all living things on land and in the sea (us included).
Lithosphere: solid earth, upper crust and mantle.
List processes that cause interactions between components of the climate system.
These components interact with each other by exchanging energy, water, momentum and carbon, thus creating a complex coupled system. The atmospheric composition affects heating and cooling of the earth, which affects the temperature and circulation of the winds and oceans. Circulation of air and sea affect temperatures and precipitation over ocean and land which impact biosphere and cryosphere. Water from melting ice flows through rivers affecting salinity, density and movement. Humans influence climate through emissions of greenhouse gases, aerosols and land use changes.
Why is Paleoclimate research important?
We want to know if the changes observed in the recent past are unusual compared to pre-industrial climate variability.
Paleoclimate research is able to extend the climate data back in time much further than the instrumental record and has delivered a fascinating history of past climate changes. Paleoclimate research is also important for a fundamental understanding of how the climate system works and what the impacts of large climate changes could be.
What are some examples of paleoclimate proxies?
Examples of proxies are:
pollen: found in lake sediments that can be used to reconstruct past vegetation cover, that in turn can be related to temperature and precipitation.
Fossil shells of planktic foraminifera: different species like different water temperatures. If shells of cold-loving foraminifera are found at a site where currently warm-loving species live, it suggests that near surface temperatures in the past have been colder.
Chemical proxies: the ratio of magnesium to calcium, which is related to temperature, or isotopes of oxygen or carbon in the calcium carbonate shells of foraminifera, which can be used to reconstruct temperature, salinity, ice volume and carbon cycling.
What is a paleoclimate archive?
Proxies are found in different archives like: tree-rings, ice-cores, corals, ocean or lake sediments.
Tree-rings, corals and speleothems (cave deposits such as stalactites and stalagmites) provide reconstructions at annual to decadal resolution back many thousands of years.
Ice cores have typically decadal to centennial resolution going back almost a million years for Antarctica and about 100,000 years for Greenland.
Ocean sediment cores cover millions of years in the past but usually at low temporal resolution of centennial to millennial timescales.
What is the Last Glacial Maximum (LGM)?
The height of the last ice age, (LGM) roughly 20.000 years ago.
What is the Holocene?
Roughly the last 10.000 years.
List the main facts about the sun.
The Sun is a yellow dwarf star of spectral type G2 (one of about 100 million in the Milky Way alone) formed about 4.6 billion years ago and composed mainly of hydrogen and helium.
Size of the sun: radius of 700,000 km
Surface temperature: 5.800K
The frightening energy emitted by the Sun comes from the thermonuclear fusion of hydrogen into helium that occurs in its innermost part: the nucleus. Here the most frequent element is helium, while hydrogen is continuously consumed in the fusion process. The amount of hydrogen still present is sufficient to keep the Sun in its current state of size and brightness for another five billion years.
How do sun spots work?
Sunspots are dark, planet-sized regions that appear on the “surface” of the Sun. Sunspots are “dark” because they are cooler than their surroundings. A large sunspot might have a central temperature of 4,000 K (about 3,700° C or 6,700° F), much lower than the 5,800 K (about 5,500° C or 10,000° F) temperature of the adjacent photosphere. Sunspots are only dark in contrast to the bright face of the Sun.
Sunspots form over periods lasting from days to weeks, and can persist for weeks or even months before dissipating. The average number of spots visible on the face of the Sun is not constant, but varies in a multi-year cycle. Historical records of sunspot counts, which go back hundreds of years, verify that this sunspot cycle has an average period of roughly eleven years.
What is the Habitable zone?
A region surrounding a star where it is theoretically possible for an Earth-like planet to have liquid water on its surface, hence support life
→ A planet’s surface temperature depends not only on its proximity to its star but also on other factors!
What is the composition of seawater?
96.5% water, 3.5% dissolved salts, particles, gases, organic matter.
