meteorology ch15 critical questions and review questions

What is the general consensus in the scientific community with regards to the current global climate change trend?

A warming trend has generally prevailed since the early 1900s.

Why does an extensive winter snow cover tend to be self-sustaining?

A winter snow cover can feed back on its environment by reflecting away solar radiation. Fresh-fallen snow typically reflects 80% or more of incident solar radiation, substantially reducing the amount of solar heating and lowering the daily maximum air temperature. Snow is also an effective emitter of infrared radiation, so infrared radiation is efficiently emitted to space, especially on nights when the sky is clear. Moreover, persistent snow cover may be further enhanced by tracks of extratropical cyclones that have a higher likelihood of following the margins of a regional snow cover, where horizontal air temperature gradients are relatively sharp. This places snow-covered regions on the cold, snowy side of migrating winter storms, thereby adding to the snow cover and reinforcing the chilled air.

Identify the various ways whereby plate tectonics may cause large-scale climate change.

. As plates move, the continents they carry also move, causing some to change latitude. This alters the local and regional radiation budget and the response of air temperature. Plate tectonics also cause ocean basins to open and close, changing the course of heat-transporting ocean currents and altering the thermohaline circulation. Plate tectonics are also responsible for building mountain ranges, which change elevation and atmospheric circulation patterns, and triggering volcanic eruptions, which alter the composition of the atmosphere.

Explain how the ice-albedo feedback affects the extent of Arctic sea-ice cover.

As seen in Figure 15.19, the ice-albedo feedback is a mechanism that accelerates melting of sea ice and amplifies warming. Sea ice insulates overlying air from warmer seawater and reflects much more incident solar radiation than ocean water. The albedo of snow-covered sea ice is about 85% whereas ice-free Arctic Ocean water has an average albedo of 40%. As sea ice cover shrinks, the greater area of ice-free ocean waters absorbs more solar radiation, sea-surface temperatures rise, and more ice melts. Furthermore, warmer water requires additional cooling before the onset of ice formation in autumn. This positive feedback mechanism rapidly reduces Arctic sea-ice cover, and greatly alters the flux of heat energy and moisture between the ocean and atmosphere.

Why is vulnerability to climate changes region specific?

Climate change is geographically non-uniform, in both magnitude and sign, affecting ecosystems and peoples throughout the world differently.

. Why is climate considered the state of a system?

Climate contains five major components, the atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere, and the interactions amongst them. Climate establishes environmental conditions and set the boundaries of weather.

How does climatology follow the scientific method?

Climate scientists propose a hypothesis (or supposition) as an explanation for climate events and variations, collect observations of climate, and design experiments to assess those hypotheses. Ultimately, predictions can be made from tested hypotheses, and the process must be repeated for verification. Repeating the process with the same methods and achieving the same results validates them. The climate system is inherently chaotic with many interlaced sub-systems on multiple spatial (space) and temporal (time) scales. The scientific method allows scientists to investigate this web of interconnections to identify the reasons for climate variability and change.

2. What is climate variability?

Climate variability is a change in the average state of the climate on all spatial and temporal scales, separate from singular weather events. Variability may be due to natural internal processes within the climate system or to variations in natural or anthropogenic (human) external forcing.

Why is mathematics used so extensively in modeling experiments?

Global climate models (GCMs) are essentially sets of mathematical equations. They work by fragmenting a map of Earth into gridded spatial coordinates resulting in a three-dimensional representation of the climate system. Essential climate variables are computed at each grid point and predicted into the future. A time step is an interval between one set of solutions and the next, and is a function of the grid spacing utilized in the GCMs. The smaller the grid spacing, the shorter the time interval that can be used to make the next calculation into the future, necessitating more calculations to achieve the desired future outcome. The physical evolution of some simple systems can be determined precisely by solving a specific mathematical equation. Other systems are too complex to be described by a single mathematical formula. In these cases, statistics approximates some of the behavior of the system on a computer (e.g., parameterization). Refer to Figure 10.5 for a visual example of these processes

What is essential in constructing a global climate model?

Global climate models require representative, observational data because models are only as good as the input data.

Explain why climate can't truly be defined as simply "average weather."

Many mechanisms can cause the state of the climate system to be different than a simple, calculated average. Moreover, no single explanation describes all climatic variability. Ranges of both climate variation and climate change are a response to the interactions of a multitude of factors, operating both internally and externally, relative to the systems and sub-systems that make up Earth's climate. Variability is inherent to climate on many scales.

What are Milankovitch cycles?

Milankovitch cycles are regular variations in the precession and tilt of Earth's axis as well as the eccentricity of its orbit, caused by the gravitational influence of the Moon and the Sun on Earth.

In general, how do the Milankovitch cycles affect incoming solar radiation?

Milankovitch cycles do not appreciably alter the total annual amount of solar energy received by Earth's planetary system, but these orbital variations significantly change the distribution of incoming solar radiation by latitude and season. Milankovitch proposed that glacial climatic episodes began when the Earth-Sun geometry favored an extended period of increased solar radiation in winter and decreased solar radiation in summer, at 65 °N. He created a numerical model from the three orbital cycles showing that more intense winter radiation in eastern Canada translated into relatively higher temperatures, higher humidity, and more snowfall. Weaker solar radiation in summer meant that some of the winter snow cover, especially north of 65 °N, survived summer and a succession of many such cool summers favored formation of a glacier.

What is the purpose of peer review?

Peer review in the sciences consists of evaluation by experienced, objective, and professional reviewers in the discipline under study to maintain high levels of quality and credibility.

What are some major differences between the WAIS and EAIS and their rate of melt in a warming climate?

Refer to Figure 15.33. The EAIS is the larger of the two ice sheets, accounting for about two-thirds of the ice in Antarctica. Unlike the EAIS, the WAIS does not reside on as much land surface. It sits on a series of islands and the floor of the Southern Ocean with parts of the ice sheet more than 1.7 km (1 mi) below msl. However, since the EAIS accounts for more ice mass, it has the potential to raise sea level more than the WAIS, if completely melted. Research shows that the EAIS has likely been more stable than the WAIS for the past 30 million years and remains fairly stable today. The WAIS has undergone episodes of rapid disintegration and may have completely melted at least once in the past 600,000 years. Another contrast between the WAIS and the EAIS is their relative rate of decline (i.e., melting trend). Recent research shows that it is likely the current trend of WAIS melting is in an irreversible state of decline, with nothing to stop the glaciers in this area from melting into the sea. Much of the potential disintegration of the EAIS is "held back" by the topography. A coastal rim of ice clamps much of EAIS ice shelf in place, somewhat similar to a cork in a bottle. The topography, however, acts to slope the bottle, or ice, downward to the sea. The removal of a specific coastal ice volume, equivalent to less than 80 mm (3.15 in) of global sea-level rise at the margin of the Wilkes Basin (EAIS), will destabilize the regional ice flow and lead to a self-sustained discharge of the entire basin and a global sea-level rise of 3 to 4 m (10 to 13 ft). Thus, the EAIS is quite possibly a future, large contributor to sea-level rise however, it will take multiple centuries for it to fully melt.

How has the Arctic environment already been affected by a changing climate?

Refer to Figure 15.42. Besides hydrologic changes in the Arctic environment, there are significant food web and societal ramifications in the Arctic environment. One particular group, which has been dramatically affected by changes in the Arctic, are the Inuit peoples of Canada. Lesser amounts of Arctic sea ice affect wildlife migration patterns of which the Inuit depend for much of their food source. Moreover, the melting of permafrost has hindered access to roads, which affects food availability. The changes in the Arctic hydrologic cycle have altered fishing opportunities and fresh water drinking sources. Many Inuit have even reported more sunburn and rashes, due to increased UV exposure. There is much less diversity amongst species in this region, relative to warmer, more tropical regions. However, research has found that there has already been a poleward range expansion of various parasites (and accordant hosts) where the Arctic has warmed. With new parasites essentially invading a less diverse Arctic ecosystem, new diseases are emerging, leaving others unable to cope or compete with these changes.

How do violent volcanic eruptions rich in sulfur dioxide (SO2) affect the stratospheric ozone shield?

SO2 from volcanic eruptions combine with water vapor to form tiny droplets of sulfuric acid (H2SO4) and sulfate particles, collectively called sulfurous aerosols. The small size of sulfurous aerosols, averaging about 0.1 µm in diameter, coupled with the absence of precipitation in the stratosphere, allow sulfurous aerosols to remain suspended in the stratosphere for months to perhaps a year or longer before they cycle out of the atmosphere to Earth's surface. In the presence of chlorine, sulfurous aerosols destroy ozone (O3), allowing more solar UV radiation to reach Earth's surface.

Describe the Maunder minimum and its possible connection to the climate of the Little Ice Age.

The Maunder minimum is a roughly 70-year period (1645 to 1715) of greatly reduced solar activity, which coincided with a cold episode in Europe. In addition to a prior 90-year period of reduced sunspot number (Spörer minimum, 1460 to 1550), the Maunder minimum occurred about the same time as relatively cold phases of the Little Ice Age in western Europe. The Dalton minimum (1790 to 1830) is another established period of lesser solar activity, coinciding with an interval of lower global temperatures.

How long is a sunspot cycle?

The time between successive sunspot maxima or minima averages approximately 11 years.

How do volcanoes influence climate change?

Volcanoes add solid particulates to the atmosphere, in addition to adding sulfur dioxide, which when combined with water, will yield sulfuric acid. Particulates of sulfur can remain suspended in the stratosphere for long periods of time and can impact earth's radiation balance.