Warhammer Fantasy Battle Reporter Forum

The effect of the moon on weather is indirect in that the moon affects
ocean tides that can alter ocean currents that can affect weather. To your
second question, yes also, the gravitational pull of the moon does produce
atmospheric "tides"; however, the effect, while measurable is small and
overwhelmed by other atmospheric factors. Another effect, that while known
and measured for several decades at least, has recently begun to receive
more attention by geologists is the tidal effect of land masses. In
particular new satellites that can measure the topology of the earth show
unmistakable "ups and downs" due to the gravitational pull of the moon. It
has been hypothesized that these small shifts might be correlated with
earthquakes and/or volcanic activity.

That the Sun plays a critical part in the Earth's climate system is indisputable. It does so in the following ways:

1. The suns rays touch the earth's surface and warm it up from an otherwise uninhabitable -250 degrees centigrade to -18 degree centigrade. These rays touch the earth's surface and reflect back to outer space. However, on the way back, the greenhouse gasses present in the atmosphere trap a further portion of this heat, in the form of infrared radiation. This further raises the average surface temperature to a more comfortable 15 degree centigrade. In this way, the Sun's radiation and the Earth's blanket of greenhouse gases sustain the mean global temperature at a level supportive of life.

2. The temperature in the earth is not constant. It varies with both time and place, and this again depends on the heat from the sun. How the Earth's surface temperature adjusts to a given change in solar radiation depends on the processes by which the climate system responds to variations in the energy it receives.

The difference in temperatures depend on the tilt of the earth away from the sun that impacts the quantum of sun's rays that fall on the specific surface, the rotation of the earth and other factors. This phenomenon influences the circulation of ocean currents, winds and convention, integral to the earth's weather process, and is the basis for different seasons like summer, winter, spring, and autumn.

3. The energy from the sun heats up the air and influences the pressure of the air. Warm air is less dense than cool air, and rises above it. This means that the air pressure above the equator, where the sun's rays fall the most is lower than the air pressure above the poles, where the sun's rays fall the least. Such differences in air pressures occur everywhere, depending on the intensity of the sun's heat. This air pressure difference results in formation of winds. Winds transport moisture laden clouds from one place to other and have a profound impact on the weather.

4. The heat generated by the sun facilitates the water cycle, upon which climate depends. When the sun's energy heats up the oceans, water evaporates and the vapors rise to the upper levels of the atmosphere. On encountering the cool air at the higher altitudes, these vapors condense as clouds. When the amount of moisture in the clouds become dense, they precipitate in the form of rains, snow, hail, thunderstorms and the like.Thunderstorms form when this process happens rapidly and with a greater intensity. When the surface heats up greatly, moisture-laden air rises very high into the atmosphere because of its much lower density, while cold air rushes in behind it. The rapidly ascending column of air is cooled and water condenses, but since more air has been heated and pushes up from beneath, the column grows higher and higher.

5. The sun's heat warming the air also plays its part in the phenomenon of land and sea breeze. Land heats up and cools down more quickly than the sea. During the day the air above the land heats up, becomes less dense and rises. The atmospheric pressure above the land thus drops and air moves in from above the sea, where the air pressure is higher. This causes a sea breeze. During the evening, the temperature of the land drops much faster than the sea. The air above the sea becomes hotter than the air above the land, so it rises and a breeze flows from the coast out to sea, reversing the effect.

6. Solar winds are a steady stream of energetic particles and magnetic fields that continuously flow out from the sun. When these ionized, particles reach the upper part of the earth's atmosphere they move throughout the magnetic force lines of the North and South poles. They produce glowing colors, commonly known as Aurora Borealis in the North, and Aurora Australis in the South. These particles affect the electrical properties of the planet and alter the atmosphere by changing air pressure and air circulation leading to changes in weather.

Variations in the flow of solar winds alter the amount of ozone in the stratosphere, popularly referred to as the ozone layer. Ozone absorbs the harmful ultraviolet rays of the sun, and decrease in ozone means such harmful radiation would touch the earth's surface.

The flow of solar winds is not constant. They decline at times, and when they do galactic cosmic rays readily enter the Earth's atmosphere promoting atmospheric conditions that could be responsible for cloud formation and severe weather.

7. Solar Flares are explosions deep inside the sun that burst out. When the extreme heat produced by these flares reach the earth, temperatures rise, resulting in heat waves and increase in air pressure. Solar flares are a regular occurrence. However, their frequency increases with the change in the solar cycle that happens once every eleven years.

8. At times, a bunch of plasma on the sun suddenly becomes buoyant and lifts off of the sun. This is called Coronal Mass Ejections (CME)'s. They travel faster than the solar wind and drive a shock wave ahead of them. When this CME's hit the earth, they result in geomagnetic storms and a beautiful display of auroras.

Weather is a set of all the phenomena occurring in a given atmosphere at a given time.[1] Weather phenomena lie in the troposphere.[2][3] Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods of time.[4] When used without qualification, "weather" is understood to be the weather of Earth.

Weather occurs due to density (temperature and moisture) differences between one place and another. These differences can occur due to the sun angle at any particular spot, which varies by latitude from the tropics. The strong temperature contrast between polar and tropical air gives rise to the jet stream. Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow. Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. On Earth's surface, temperatures usually range ±40 °C (100 °F to −40 °F) annually. Over thousands of years, changes in Earth's orbit affect the amount and distribution of solar energy received by the Earth and influence long-term climate

Surface temperature differences in turn cause pressure differences. Higher altitudes are cooler than lower altitudes due to differences in compressional heating. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The atmosphere is a chaotic system, so small changes to one part of the system can grow to have large effects on the system as a whole. Human attempts to control the weather have occurred throughout human history, and there is evidence that human activity such as agriculture and industry has inadvertently modified weather patterns.

Studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least 300 years. However, weather is not limited to planetary bodies. A star's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind.On Earth, common weather phenomena include wind, cloud, rain, snow, fog and dust storms. Less common events include natural disasters such as tornadoes, hurricanes and ice storms. Almost all familiar weather phenomena occur in the troposphere (the lower part of the atmosphere).[3] Weather does occur in the stratosphere and can affect weather lower down in the troposphere, but the exact mechanisms are poorly understood.[5]

Weather occurs primarily due to density (temperature and moisture) differences between one place to another. These differences can occur due to the sun angle at any particular spot, which varies by latitude from the tropics. In other words, the farther from the tropics you lie, the lower the sun angle is, which causes those locations to be cooler due to the indirect sunlight.[6] The strong temperature contrast between polar and tropical air gives rise to the jet stream.[7] Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow (see baroclinity).[8] Weather systems in the tropics, such as monsoons or organized thunderstorm systems, are caused by different processes.Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. In June the Northern Hemisphere is tilted towards the sun, so at any given Northern Hemisphere latitude sunlight falls more directly on that spot than in December (see Effect of sun angle on climate).[9] This effect causes seasons. Over thousands to hundreds of thousands of years, changes in Earth's orbital parameters affect the amount and distribution of solar energy received by the Earth and influence long-term climate (see Milankovitch cycles).[10]

Uneven solar heating (the formation of zones of temperature and moisture gradients, or frontogenesis) can also be due to the weather itself in the form of cloudiness and precipitation.[11] Higher altitudes are cooler than lower altitudes, which is explained by the lapse rate.[12][13] On local scales, temperature differences can occur because different surfaces (such as oceans, forests, ice sheets, or man-made objects) have differing physical characteristics such as reflectivity, roughness, or moisture content.

Surface temperature differences in turn cause pressure differences. A hot surface heats the air above it and the air expands, lowering the air pressure and its density.[14] The resulting horizontal pressure gradient accelerates the air from high to low pressure, creating wind, and Earth's rotation then causes curvature of the flow via the Coriolis effect.[15] The simple systems thus formed can then display emergent behaviour to produce more complex systems and thus other weather phenomena. Large scale examples include the Hadley cell while a smaller scale example would be coastal breezes.

The atmosphere is a chaotic system, so small changes to one part of the system can grow to have large effects on the system as a whole.[16] This makes it difficult to accurately predict weather more than a few days in advance, though weather forecasters are continually working to extend this limit through the scientific study of weather, meteorology. It is theoretically impossible to make useful day-to-day predictions more than about two weeks ahead, imposing an upper limit to potential for improved prediction skill.[17] Chaos theory says that the slightest variation in the motion of the ground can grow with time. This idea is sometimes called the butterfly effect, from the idea that the motions caused by the flapping wings of a butterfly eventually could produce marked changes in the state of the atmosphere. Because of this sensitivity to small changes it will never be possible to make perfect forecasts, although there still is much potential for improvement.

The sun and oceans can also affect the weather of land. If the sun heats up ocean waters for a period of time, water can evaporate. Once evaporated into the air, the moisture can spread throughout nearby land, thus making it cooler.

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time. Climate can be contrasted to weather, which is the present condition of these same elements over periods up to two weeks.

The climate of a location is affected by its latitude, terrain, altitude, ice or snow cover, as well as nearby water bodies and their currents. Climates can be classified according to the average and typical ranges of different variables, most commonly temperature and rainfall. The most commonly used classification scheme is the one originally developed by Wladimir Köppen. The Thornthwaite system,[1] in use since 1948, incorporates evapotranspiration in addition to temperature and precipitation information and is used in studying animal species diversity and potential impacts of climate changes. The Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses defining the climate for certain areas.

Paleoclimatology is the study and description of ancient climates. Since direct observations of climate are not available before the 19th century, paleoclimates are inferred from proxy variables that include non-biotic evidence such as sediments found in lake beds and ice cores, and biotic evidence such as tree rings and coral. Climate models are mathematical models of past, present and future climates.

Definition
Climate (from Ancient Greek klima, meaning inclination) is commonly defined as the weather averaged over a long period of time.[2] The standard averaging period is 30 years,[3] but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations. The Intergovernmental Panel on Climate Change (IPCC) glossary definition is:

Climate in a narrow sense is usually defined as the "average weather," or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.[4]

The difference between climate and weather is usefully summarized by the popular phrase "Climate is what you expect, weather is what you get."[5] Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water, and proximity to oceans and mountains. These change only over periods of millions of years due to processes such as plate tectonics. Other climate determinants are more dynamic: for example, the thermohaline circulation of the ocean leads to a 5 °C (9 °F) warming of the northern Atlantic ocean compared to other ocean basins.[6] Other ocean currents redistribute heat between land and water on a more regional scale. The density and type of vegetation coverage affects solar heat absorption,[7] water retention, and rainfall on a regional level. Alterations in the quantity of atmospheric greenhouse gases determines the amount of solar energy retained by the planet, leading to global warming or global cooling. The variables which determine climate are numerous and the interactions complex, but there is general agreement that the broad outlines are understood, at least insofar as the determinants of historical climate change are concerned.

Climate classification
There are several ways to classify climates into similar regimes. Originally, climes were defined in Ancient Greece to describe the weather depending upon a location's latitude. Modern climate classification methods can be broadly divided into genetic methods, which focus on the causes of climate, and empiric methods, which focus on the effects of climate. Examples of genetic classification include methods based on the relative frequency of different air mass types or locations within synoptic weather disturbances. Examples of empiric classifications include climate zones defined by plant hardiness,[9] evapotranspiration,[10] or more generally the Köppen climate classification which was originally designed to identify the climates associated with certain biomes. A common shortcoming of these classification schemes is that they produce distinct boundaries between the zones they define, rather than the gradual transition of climate properties more common in nature.

Bergeron and Spatial Synoptic
The most generic classification is that involving the concept of air masses. The Bergeron classification is the most widely accepted form of air mass classification. Air mass classification involves three letters. The first letter describes its moisture properties, with c used for continental air masses (dry) and m for maritime air masses (moist). The second letter describes the thermal characteristic of its source region: T for tropical, P for polar, A for Arctic or Antarctic, M for monsoon, E for equatorial, and S for superior air (dry air formed by significant downward motion in the atmosphere). The third letter is used to designate the stability of the atmosphere. If the air mass is colder than the ground below it, it is labeled k. If the air mass is warmer than the ground below it, it is labeled w.[11] While air mass identification was originally used in weather forecasting during the 1950s, climatologists began to establish synoptic climatologies based on this idea in 1973.[12]

Based upon the Bergeron classification scheme is the Spatial Synoptic Classification system (SSC). There are six categories within the SSC scheme: Dry Polar (similar to continental polar), Dry Moderate (similar to maritime superior), Dry Tropical (similar to continental tropical), Moist Polar (similar to maritime polar), Moist Moderate (a hybrid between maritime polar and maritime tropical), and Moist Tropical (similar to maritime tropical, maritime monsoon, or maritime equatorial).[13]

Köppen
The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. Specifically, the primary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, steppe, subarctic climate, tundra, polar ice cap, and desert.

Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 millimetres (69 in) and 2,000 millimetres (79 in). Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year.[14]

A monsoon is a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season.[15] Regions within North America, South America. Sub-Saharan Africa, Australia and East Asia are monsoon regimes.[16]

A tropical savanna is a grassland biome located in semi-arid to semi-humid climate regions of subtropical and tropical latitudes, with average temperatures remain at or above 18 °C (64 °F) year round and rainfall between 750 millimetres (30 in) and 1,270 millimetres (50 in) a year. They are widespread on Africa, and are also found in India, the northern parts of South America, Malaysia, and Australia.[17]

The humid subtropical climate zone where winter rainfall (and sometimes snowfall) is associated with large storms that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones.[18] Humid subtropical climates lie on the east side continents, roughly between latitudes 20° and 40° degrees away from the equator.[19]

A humid continental climate is marked by variable weather patterns and a large seasonal temperature variance. Places with a hottest monthly temperature above 10 °C (50 °F) and a coldest month temperature below −3 °C (26.6 °F) and which do not meet the criteria for an arid climate, are classified as continental.[20]

An oceanic climate is typically found along the west coasts at the middle latitudes of all the world's continents, and in southeastern Australia, and is accompanied by plentiful precipitation year round.[21]

The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of western North America, parts of Western and South Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot, dry summers and cool, wet winters.[22]

A steppe is a dry grassland with an annual temperature range in the summer of up to 40 °C (104 °F) and during the winter down to −40 °C (−40.0 °F).[23]

A subarctic climate has little precipitation,[24] and monthly temperatures which are above 10 °C (50 °F) for one to three months of the year, with continuous permafrost due to the very cold winters. Winters within subarctic climates include up to six months of temperatures averaging below 0 °C (32 °F).[25]

Tundra occurs in the far Northern Hemisphere, north of the taiga belt, including vast areas of northern Russia and Canada [26].

A polar ice cap, or polar ice sheet, is a high-latitude region of a planet or moon that is covered in ice. Ice caps form because high-latitude regions receive less energy in the form of solar radiation from the sun than equatorial regions, resulting in lower surface temperatures.[27]

A desert is a landscape form or region that receives very little precipitation. Deserts usually have a large diurnal and seasonal temperature range, with high daytime temperatures (in summer up to 45 °C or 113 °F), and low night-time temperatures (in winter down to 0 °C; 32 °F) due to extremely low humidity. Many deserts are formed by rain shadows, as mountains block the path of moisture and precipitation to the desert.[28]