Mechanisms of Natural Climate Fluctuation Flashcards
What is Solar irradiance?
The Sun’s output of energy toward Earth, known as solar irradiance, varies over several time scales, and these natural variations can affect climate.
What is the length of the cycle that sunspots tend to vary?
As discussed in Chapter 2, the number of sunspots varies over an 11-year solar cycle.
What was the Maunder minimum?
Maunder Minimum (11) A solar minimum (a period with little sunspot activity and reduced solar irradiance) that lasted from about 1645 to 1715, corresponding with one of the coldest periods of the Little Ice Age. This relationship suggests a causal effect between decreased sunspot numbers and cooling temperatures in the North Atlantic region. However, research has repeatedly refuted this hypothesis (for example, recent temperature warming corresponds with a prolonged solar minimum).
What are the Earth-Sun relationships that affect climate fluctuation?
These relationships include Earth’s distance from the Sun, which varies within its orbital path, and Earth’s orientation to the Sun, which varies as a result of the “wobble” of Earth on its axis, and because of Earth’s varying axial tilt
What is eccentricity?
Earth’s elliptical orbit about the Sun, known as eccentricity, is not constant and changes in cycles over several time scales. The most prominent is a 100 000-year cycle in which the shape of the ellipse varies by more than 17.7 million km, from a shape that is nearly circular to one that is more elliptical
What is precession?
Earth’s axis “wobbles” through a 26 000-year cycle, in a movement much like that of a spinning top winding down (Figure 11.16b). Earth’s wobble, known as precession, changes the orientation of hemispheres and landmasses to the Sun.
How much dose earth’s axial tilt vary. How long of a period dose it take for this to occur?
Earth’s axial tilt, at present about 23.5°, varies from 21.5° to 24.5° during a 41 000-year period
What are Milankovitch cycles?
Milankovitch cycles (11) The consistent orbital cycles—based on the irregularities in Earth’s orbit around the Sun, its rotation on its axis, and its axial tilt—that relate to climatic patterns and may be an important cause of glacials and interglacials. Milutin Milankovitch (1879–1958), a Serbian astronomer, was the first to correlate these cycles to changes in insolation that affected temperatures on Earth
How dose Continental Position and Topography affect climate?
Because Earth’s lithosphere is composed of moving plates, continental rearrangement has occurred throughout geologic history (look ahead to Figure 12.14). This movement affects climate since landmasses substantially affect the atmosphere’s general circulation.
The relative proportions of land and ocean area affect surface albedo, as does the position of landmasses relative to the poles or equator.
Finally, the movement of continental plates causes episodes of mountain building and spreading of the seafloor. These processes affect Earth’s climate system as high-elevation mountain ranges accumulate snow and ice during glacial periods, and as CO2 from volcanic outgassing enters the atmosphere (from volcanoes) and the ocean (from spreading of the seafloor).
How dose Atmospheric Gases and Aerosols affect climate fluctuations?
Natural outgassing from Earth’s interior through volcanoes and vents in the ocean floor is the primary natural source of CO2 emissions to the atmosphere. Water vapour is a natural greenhouse gas present in Earth’s atmosphere and is discussed ahead with regard to climate feedbacks.
As greenhouse gas concentrations change, Earth’s surface heats or cools in response. Further, these gases can amplify the climatic trends
What is ENSO and how dose it affect earth?
El Niño–Southern Oscillation
-higher pressure develops over the western Pacific, and lower
pressure develops over the eastern Pacific
-Westward trade winds can be reduced or even replaced by an eastward (west-to-east) flow.
-Sea-surface temperatures may increase to more than 8 °C above normal in the central and eastern Pacific, replacing the normally cold, nutrient-rich water along Peru’s coastline
-During El Niño conditions, the thermocline lowers in-depth in the eastern Pacific Ocean, blocking upwelling currents and their nutrient-rich waters. This loss of nutrients affects the phytoplankton and food chain, depriving fish, marine mammals, and predatory birds of nourishment.
What is La Nina?
When surface waters in the central and eastern Pacific cool to below normal by 0.4 °C or more, the condition is dubbed La Niña, Spanish for “the girl.” This condition is weaker and less consistent than El Niño; otherwise, there is no correlation in strength or weakness
between the two phases.
What is the PDO and how dose it affect the earth?
- 20 to 30 years in duration, then the 2- to 12-year variation in the ENSO
- Involved are two regions of sea-surface temperatures and related air pressure: the northern and tropical western Pacific (region #1), and the area of the eastern tropical Pacific, along the West Coast (region #2).
- higher-than-normal temperatures dominated region #1, and lower temperatures were in region #2; this is the PDO negative phase (or cool phase)
- (opposite for warm phase)
What is NAO and how dose it affect earths climate?
- A north–south fluctuation of atmospheric variability marks the North Atlantic Oscillation
- pressure differences between the Icelandic Low and the Azores High in the Atlantic alternate from a weak to a strong pressure gradient
What is the AO and how dose it affect earths climate?
The Arctic Oscillation (AO) is the variable fluctuation between middle- and high-latitude air mass conditions over the Northern Hemisphere. The AO is associated with the NAO, especially in winter
