Meteorology/Climate

Overview
Meteorology is a weather based event designed to give students a basic understanding of the weather and an understanding of why the "weatherman" is always wrong. This year, severe weather is the topic of choice for this event. Good things to know about every year are fronts and air systems.

The event does not allow any resources during competition, except for a piece of paper with notes (written/typed/double-sided etc.) and a non graphing calculator. This new rule change is because of the scandal that occurred at Nationals a year ago where one team wrote down all the questions on the test in their database and gave the database to another team (obviously presenting a problem).

The event is designed for up to 2 people.

See Meteorology notes for more info. See Also Climate notesfor more climate info

Recommended Subjects for Climate [2009]

 * 1) Composition and evolution of Earth's atmosphere
 * 2) weather vs. climate
 * 3) solar radiation
 * 4) Climatic zones
 * 5) Natural climatic variability
 * 6) Oceanic and Atmospheric circulation
 * 7) Earth's celestial cycles
 * 8) Paleoclimates of Earth's geologic history
 * 9) Human impact on climate change

These subjects are only recommended and not required so you can expect questions that dont fall into any of the above categories. Also be able to read different forms of charts graphs and tables.

Remember that these topics are what is RECOMMENDED, not necessarily what actually shows up on the test.

Scoring
Obviously, the team with the most correct answers win. Tie breaker questions are limited to 5.

Topics
The meteorology topics cycle yearly in order to present students with a comprehensive course of the meteorological sciences. Ideally, students should have been on this event last year to be able to fully grasp this year's event.

General Weather/ Climate
General Weather/Climate- Average Daily Temperature- average of daily high and low, Average Monthly Temperature- average of the ADTs of a month, Yearly Average Temperature- averaging the 12 AMTs. Daily Temperature range- difference between the day�s high and low. Yearly temp. Range- difference between the average of the warmest and coldest month. Climate= a region�s composite weather

Koppen Climate Classification

 * K�ppen Climate Classification-
 * GROUP A: Tropical/megathermal climates- Tropical rain forest climate (Af), Tropical monsoon climate (Am), Tropical wet and dry or savanna climate (Aw)
 * GROUP B: Dry (arid and semiarid) (climate�s precipitation is less than potential evapotranspiration)- Subtropical desert (Bwh), Subtropical steppe (Bsh), Mid-Latitude desert (Bwk), Mid-Latitude Steppe (Bsk)
 * GROUP C: Temperate/mesothermal climates- Mediterranean climates (Csa, Csb), Humid subtropical climates (Cfa, Cwa), Maritime Temperate climates or Oceanic climates (Cfb, Cwb, Cfc), temperate climate with dry winters (Cwb), Maritime Subarctic climates or Subpolar Oceanic climates (Cfc)
 * GROUP D: Continental/microthermal climate- Hot Summer Continental climates (Dfa, Dwa, Dsa), Warm Summer Continental or Hemiboreal climates (Dfb, Dwb, Dsb), Continental Subarctic or Boreal (taiga) climates (Dfc, Dwc, Dsc)
 * GROUP E: Polar climates- Tundra climate (ET), Ice Cap climate (EF)
 * GROUP H: Highland climates, in which altitude plays a role in determining climate classification

Solar Radiation/ Earth�s Energy Balance
Sunlight is the source of energy for the Earth�s oceans, atmosphere, land, and biosphere. This energy serves to heat the Earth to temperatures far above the minus 454 degrees Fahrenheit (3 degrees Kelvin) of deep space. Averaged over an entire year and the entire Earth, the sun deposits 342 Watts of energy into every square meter of the Earth. This energy is output form the sun I the form of short-wave radiation, and is absorbed and reflected by earth as long-wave radiation.

Atmospheric Composition/ Evolution
Nitrogen-78.08%, oxygen 20.95%, argon 0.93%, carbon dioxide 0.038%, trace amounts of other gases, and water vapor, on average around 1%. The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from previous compositions. The original atmosphere was primarily helium and hydrogen. Heat from the still-molten crust, the sun, and a probably enhanced solar wind, dissipated this atmosphere. About 4.4 billion years ago, the surface had cooled enough to form a crust. It was heavily populated with volcanoes, which released steam, carbon dioxide, and ammonia. This led to the early "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. This second atmosphere had approximately 100 times as much gas as the current atmosphere, but as it cooled much of the carbon dioxide was dissolved in the seas and precipitated out as carbonates. The later "second atmosphere" contained largely nitrogen and carbon dioxide. However, simulations run at the University of Waterloo and University of Colorado in 2005 suggest that it may have had up to 40% hydrogen. It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide and methane, kept the Earth from freezing. This oxygen-nitrogen atmosphere is the "third atmosphere". Between 200 and 250 million years ago, up to 35% of the atmosphere was oxygen (as found in bubbles of ancient atmosphere preserved in amber). Greenhouse Gasses- When these gases are ranked by their contribution to the greenhouse effect, the most important are:
 * water vapor, which contributes 36�70%
 * carbon dioxide, which contributes 9�26%
 * methane, which contributes 4�9%
 * ozone, which contributes 3�7%

Natural Climatic Variability
Temperature controls: Latitude- main factor, higher the latitude, the lower the average yearly temperature and larger the yearly temperature range. Altitude- average rate of decrease is 5.5� per 1000 feet of altitude. Land/sea boundary- land areas hot summers and cold winters, sea areas have cooler summers and milder winters. Prevailing winds- moderates temperature; effect doesn�t extend past the first high mountain range. Warm or cold ocean currents can affect the temperature of an area. Rainfall Controls: Latitude-wet belt or dry belt, mountains- windward sides are rainy, leeward (rain shadow) are dry descending winds are called chinooks, and foehns, distance from the sea- not a guarantee, drier near interior of continent.

El Ni�o and La Ni�a
El Ni�o and La Ni�a are officially defined as sustained sea surface temperature anomalies of magnitude greater than 0.5�C across the central tropical Pacific Ocean. When the condition is met for a period of less than five months, it is classified as El Ni�o or La Ni�a conditions; if the anomaly persists for five months or longer, it is classified as an El Ni�o or La Ni�a episode. Historically, it has occurred at irregular intervals of 2-7 years and has usually lasted one or two years. The first signs of an El Ni�o are: 1. Rise in air pressure over the Indian Ocean, Indonesia, and Australia 2. Fall in air pressure over Tahiti and the rest of the central and eastern Pacific Ocean 3. Trade winds in the south Pacific weaken or head east 4. Warm air rises near Peru, causing rain in the northern Peruvian deserts 5. Warm water spreads from the west Pacific and the Indian Ocean to the east Pacific. It takes the rain with it, causing extensive drought in the western Pacific and rainfall in the normally dry eastern Pacific. El Ni�o's warm current of nutrient-poor tropical water, heated by its eastward passage in the Equatorial Current, replaces the cold, nutrient-rich surface water of the Humboldt Current, also known as the Peru Current, which support great populations of food fish. In most years the warming lasts only a few weeks or a month, after which the weather patterns return to normal and fishing improves. However, when El Ni�o conditions last for many months, more extensive ocean warming occurs and its economic impact to local fishing for an international market can be serious. During non-El Ni�o conditions, the Walker circulation is seen at the surface as easterly trade winds, which move water and air warmed by the sun towards the west. This also creates ocean upwelling off the coasts of Peru and Ecuador and brings nutrient-rich cold water to the surface, increasing fishing stocks. The western side of the equatorial Pacific is characterized by warm, wet low-pressure weather as the collected moisture is dumped in the form of typhoons and thunderstorms. The ocean is some 60 cm higher in the western Pacific as the result of this motion. In the Pacific, La Ni�a is characterized by unusually cold ocean temperatures in the eastern equatorial Pacific, compared to El Ni�o, which is characterized by unusually warm ocean temperatures in the same area. Atlantic tropical cyclone activity is generally enhanced during La Ni�a. The La Ni�a condition often follows the El Ni�o, especially when the latter is strong.

Thermohaline Circulation
The term thermohaline circulation (THC) refers to the part of the large-scale ocean circulation that is thought to be driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of sea water. Wind-driven surface currents (such as the Gulf Stream) head polewards from the equatorial Atlantic Ocean, cooling all the while and eventually sinking at high latitudes (forming North Atlantic Deep Water). This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters (with a transit time of around 1600 years) upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's ocean a global system. On their journey, the water masses transport both energy (in the form of heat) and matter (solids, dissolved substances and gases) around the globe. As such, the state of the circulation has a large impact on the climate of the Earth. The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt. On occasion, it is used to refer to the meridional overturning circulation (often abbreviated as MOC). Formation and movement of the deep water masses at North Atlantic Ocean, creates sinking water masses that fills the basin and flows very slowly into the deep abyssal plains of the Atlantic. This high latitude cooling and the low latitude heating drives the movement of the deep water in a polar southward flow. The deep water flows through the Antarctic Ocean Basin around South Africa where it is split into two routes: one into the Indian Ocean and one past Australia into the Pacific. At the Indian Ocean, some of the cold and salty water from Atlantic -- drawn by the flow of warmer and fresher upper ocean water from the tropical Pacific -- causes a vertical exchange of dense, sinking water with lighter water above. It is known as overturning. In the Pacific Ocean, the rest of the cold and salty water from the Atlantic undergoes Haline forcing and slowly becomes warmer and fresher. The out-flowing undersea of cold and salty water makes the sea level of the Atlantic slightly lower than the Pacific and salinity or halinity of water at the Atlantic higher than the Pacific. This generates a large but slow flow of warmer and fresher upper ocean water from the tropical Pacific to the Indian Ocean through the Indonesian Archipelago to replace the cold and salty Antarctic Bottom Water. This is also known as Haline forcing (net high latitude freshwater gain and low latitude evaporation). This warmer, fresher water from the Pacific flows up through the South Atlantic to Greenland, where it cools off and undergoes evaporative cooling and sinks to the ocean floor, providing a continuous thermohaline circulation. Hence, a recent and popular name for the thermohaline circulation, emphasizing the vertical nature and pole-to-pole character of this kind of ocean circulation, is the meridional overturning circulation.

Milankovitch Cycles

 * Axial Tilt- The angle of the Earth's axial tilt (obliquity) varies with respect to the plane of the Earth's orbit. These slow 2.4� obliquity variations are roughly periodic, taking approximately 41,000 years to shift between a tilt of 22.1� and 24.5� and back again. When the obliquity increases, the amplitude of the seasonal cycle in insolation (INcoming SOLar radiATION) increases, with summers in both hemispheres receiving more radiative flux from the Sun, and the winters less radiative flux. As a result, it is assumed that the winters become colder and summers warmer. But these changes of opposite sign in the summer and winter are not of the same magnitude. The annual mean insolation increases in high latitudes with increasing obliquity, while lower latitudes experience a reduction in insolation. Cooler summers are suspected of encouraging the start of an ice age by melting less of the previous winter's ice and snow. So it can be argued that lower obliquity favors ice ages both because of the mean insolation reduction in high latitudes as well as the additional reduction in summer insolation.
 * Eccentricity- The Earth's orbit is an ellipse. The eccentricity is a measure of the departure of this ellipse from circularity. The shape of the Earth's orbit varies from being nearly circular (low eccentricity of 0.005) to being mildly elliptical (high eccentricity of 0.058) and has a mean eccentricity of 0.028 (or 0.017 which is current value). The major component of these variations occurs on a period of 413,000 years (eccentricity variation of �0.012). A number of other terms vary between 95,000 and 136,000 years, and loosely combine into a 100,000-year cycle. The present eccentricity is 0.017.
 * Precession- Precession is the change in the direction of the Earth's axis of rotation relative to the fixed stars, with a period of roughly 26,000 years. This gyroscopic motion is due to the tidal forces exerted by the sun and the moon on the solid Earth, associated with the fact that the Earth is not a perfect sphere but has an equatorial bulge. The sun and moon contribute roughly equally to this effect. In addition, the orbital ellipse itself precesses in space (anomalistic precession), primarily as a result of interactions with Jupiter and Saturn. This orbital precession is in the opposite sense to the gyroscopic motion of the axis of rotation, shortening the period of the precession of the equinoxes with respect to the perihelion from 25,771.5 to ~21,636 years.

Links
New York Coaches Conference
 * Koppen Scale
 * http://geography.about.com/library/weekly/aa011700b.htm
 * http://koeppen-geiger.vu-wien.ac.at/