Weather 2 Flashcards
Forcing
when there is an imbalance between the absorption of solar radiation and energy emitted by the top of the earth’s atmosphere (The cause)
Feedback
is the reaction of the climate system to the forcing.
Weather
the state of the atmosphere at any given place and time
Climate
the average state of the weather, on time scales of seasons and longer (often expressed as 30-year averages)
Climate proxies
a source of information from natural and human records that can be used to estimate past climate conditions
Examples of proxies
instrumental, historical, tree-rings, ice-cores, lake sediments, coral reefs, ocean sediments, continental coastal sediments
Natural proxies examples
trees (tree ring correlate to climate and stable isotope can provide temperature) and corals (coral annual growth signs can provide temperature and sea level)
Varves
distinct laminated beds on some lake sediments that have annual layers that contain several proxies
Plant spore proxies
pollen and spores have a hard waxy coating that resists weathering that can reveal the climatic conditions
Ice cores
Provide a continuous record of climate from 80 thousand years ago. Gas bubbles in ice preserve past atmospheric conditions, stable isotopes of O and H of the ice are used.
Marine cores
deep-sea sediment cores provide missions of years of records of climate. Shells of plankton contain CaCO3 with proportions of O18 and O16 which are preserved. The ratio of O18 to O16 in seawater depends on water temperature and ice volume on land.
What controls long-term climate
tectonic forcing
What controls short-time scale climate
milankovitch cycles and solar cyces
Climate Forcing
any process or disturbance that drives changes in climate
Examples of external climate forcing
tectonic, orbital, solar, volcanism, anthropocentric
Examples of internal climate forcing
greenhouse gases, aerosols, albedo, ocean-atmosphere circulation patterns
Difference between internal and external climate forcing
Internal forcing occurs within the natural climate cycle
Earth’s climate fluctuates between ____ and ____ states
greenhouse, and icehouse
Two mojor external factors control short term climate
solar variation and milankovich cycles
Milankovich cycles
due to minor variations in Earth’s orbit and in the tilt of the earth’s axis controls the distribution of solar irradiation over the earth’s surface.
Eccentricity
a measure of Earth’s orbit departure from circularity. It influences the perihelion (when the earth is nearest to Sun) and aphelion (when the earth is farthest from the sun).
Tilt
Earth’s axis tilt influenced the extent to which a given portion of the earth’s surface points away or toward the sun at any given time.
Earth’s tilt range
between 24.75 and 21.27
Precession
the direction of the tilt of the earth rotates relevant to the earth’s elliptical orbit.
____ changes the timing of the winter and swimmer solstices and fall and spring equinox.
precession
Quaternary glaciation
marks the start of large-scale Northern Hemisphere glaciation at ~2.6 million years ago
Glacial-integration cycles
Are driven by initial increases in temperature by Milankovich cycles but are driven by an increase in CO2 concentrations that drive other feedbacks
glacial/interglacial cycles happen every ____ years
100 thousand
