DOCSLIB.ORG

The Heat Balance of the Earth and the Seasons

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Heat Balance of the Earth and the Seasons T. James Noyes, El Camino College Clouds and Rain Unit (Topic 8A-2) – page 1 Name: Clouds and Rain Unit (3 pts) Section: As air rises, it cools due to the reduction in atmospheric pressure Air mainly consists of oxygen molecules and nitrogen molecules. Remember that warm molecules move faster than cold molecules. This allows warm air molecules to push aside nearby molecules and spread out, which lowers their density and causes them to rise. Atmospheric pressure is caused by the weight of the air above. Up in the mountains, air pressure is lower, because there is less atmosphere above you (less air pressing down on top of you). Therefore, as warm air rises higher into the atmosphere, it experiences lower pressure. Since the group of warm, rising air molecules are no longer being squeezed together as strongly by the air above, the group of warm, rising air molecules pushes outward. In other words, the warm air expands as it rises. However, in pushing outward against the neighboring cooler air molecules, the warm, rising air molecules give some of their energy to the neighboring air, causing the warm, rising air to cool down. In short, rising air cools due to the decrease in atmospheric pressure. Experiment: Blow into your hand. First, keep your mouth opening small, then open wide as if yawning. In which case does the air feel warm? In which case does it feel cool? When the opening is small, the air is forced together, and quickly expands once outside your mouth. If the water molecules in the air cool down enough, they will begin to bond with one another. (The water molecules are no longer moving fast enough to fly apart when they get too close to one another and bonds form between them.) Thus, rising air produces cloudy and rainy skies. As the rising air cools down more and more, it loses its water as rain. By the time the air sinks, it is completely dry. Dry air cannot produce clouds or rain. Note: In most situations water vapor needs additional help from aerosols to condense. (Aerosols are tiny solid particles like dust or drops of liquid in the air.) It is easier for water molecules to bond with bigger, slower-moving objects like aerosols. The kind and size of aerosols available can have a big impact on whether clouds form and rain occurs, as well as how much rain occurs. T. James Noyes, El Camino College Clouds and Rain Unit (Topic 8A-2) – page 2 1. As air rises, does it become warmer or cooler? 2. Does water vapor cool and condense into clouds and rain when air rises or when air sinks? Convection Cells, and Cloudy Skies and Clear Skies In the previous Unit, we learned that as air rises, it cools, causing the water vapor in the air to condense into clouds and rain (if enough water vapor is present in the air). If we apply this idea to a convection cell, clouds and rain will be more common above the warm spot, the place where air is rising. The sinking air at the cold spot will have little or no water vapor, because the water vapor was lost at the warm spot when it condensed into clouds and rain. In addition, the air at the cold spot warms as it sinks (due to the increase in pressure). So, clear skies will be more common above the cold spot. T. James Noyes, El Camino College Clouds and Rain Unit (Topic 8A-2) – page 3 Air Temperature, Pressure, Cloudy Skies, and Clear Skies If you listen to weather reports, you may be familiar with the fact that low pressure zones are associated with clouds and rain, and high pressure zones are associated with clear skies. Beneath regions of warm, low-density, rising air, the pressure at the surface of the Earth is lower. (There are fewer air molecules above.) Beneath regions of cold, high-density, sinking air, the pressure at the surface of the Earth is higher. (There are more air molecules above.) Here is another way to think about this: If the air is rising (going up), then the air is not pressing down very hard, and if the air is sinking (going down), then the air is pressing down harder. We have learned that warm, rising air produces cloudy and rainy skies, and that warm air exerts lower pressure, so lower air pressure at the surface is associated with cloudy and rainy skies. Cool, sinking air produces clear skies, and cool air exerts higher pressure, so higher pressure is associated with clear skies. Also, note that we learned in the previous Unit that air moves from the colder spot to the warmer spot to replace the air rising at the warm spot. In other words, winds blow away from the colder spot and towards the warmer spot. Since the air at the colder spot exerts higher pressure and the air at the warmer spot exerts lower pressure, this means that surface winds blow from the place with higher pressure at the surface towards the place with lower pressure at the surface. 3. Where are the cloudy and rainy skies, at the warm spot or at the cold spot? 4. Where are the clear skies, at the warm spot or at the cold spot? 5. Where is the surface air pressure higher, at the warm spot or at the cold spot? 6. When do we typically get more clouds and rain, when air pressure is higher or lower? 7. Does air move from the place with lower pressure at the surface to the place with higher pressure at the surface, or does air move from the place with higher pressure at the surface to the place with lower pressure at the surface? In other words, do winds blow towards the place with lower pressure or towards the place with higher pressure? T. James Noyes, El Camino College Clouds and Rain Unit (Topic 8A-2) – page 4 The Global Rainfall Pattern You need to be familiar with the global rainfall pattern shown on the right, as well as the global wind pattern. If you know where surface winds come together and the air rises, then you know where it is cloudy and rainy. Similarly, where surface winds move apart, air sinks, and the skies are clearer. Remember that the dotted arrows show air rising and sinking (air going towards or away from the surface of the Earth). Air rises at the Equator since it is the warmest place in the world. As the air rises, it cools, and this causes water in the air to condense into clouds and rain. Hence, the Equator is where we find tropical rainforests. At the cold Poles, air sinks and thus there are clear skies. Air moving away from the Poles and Equator turns under the influence of the Coriolis effect, so it cannot travel all the way from the Equator to the Poles or from the Poles to the Equator. As a result, air sinks at 30oN and 30oS where it is cooler than the Equator, and air rises at 60oN and 60oS where it is warmer than the Poles. The rising air at 60oN and 60oS leads to cloudy and rainy skies at these latitudes, and the sinking air at 30oN and 30oS leads to clear skies at these latitudes. To help remember this, think of southern California and Seattle. Los Angeles is close to 30oN, so we typically have clear skies. Seattle is the closest big city to 60oN along the west coast of the United States, and is known for its gray skies and rain. 8. At what latitudes does air rise? 9. At what latitudes does air sink? 10. At which latitudes are cloudy and rainy skies more common? 11. At which latitudes are clear skies more common? T. James Noyes, El Camino College Clouds and Rain Unit (Topic 8A-2) – page 5 Weather, Climate, & Fronts Up till now, we have been discussing climate, not weather. Climate is the long-term average of weather conditions (what the weather is usually like). For example, Southern California has a warm, dry climate with clear skies. This does not mean that it is always warm or that it does not rain in Southern California. It means that our weather is warm most of the time and that rain is less common here than elsewhere. Here is another way to think about it: Weather is what conditions are like on a particular day, while climate is what conditions are like during a season or a year. Your own experience of actual storms and rain may contradict something that I said before. I claimed that warm, rising air leads to clouds and rain. Many of you may say: “Wait a minute. It rains when the weather is cold.” Storms often form along what meteorologists call fronts, a place where 2 air masses meet. An air mass is a collection of air with similar properties (like temperature and water vapor content), often determined by where it comes from. For example, warm, moist air moves up into the United States from the Gulf of Mexico, while cool, dry air comes down from Canada. We also use the word front to describe the location where two opposing armies meet and are shooting at one another. As in the military, the frontlines for weather typically are where the action is (clouds, rain, hail, snow, and so on). At the locations where air masses meet (the front), the cooler air pushes the warmer air up, sliding in underneath to replace it, or the warmer air can move up and over the cooler air.
Load more

Recommended publications
  • Atmospheric Circulation
    Atmospheric circulation Trade winds http://science.nasa.gov/science-news/science-at-nasa/2002/10apr_hawaii/ Atmosphere (noun) the envelope of gases (air) surrounding the earth or another planet Dry air: Argon, 0.98% O2, 21% N2, 78% CO2, >400ppm & rising Water vapor can be up to 4% 50% below 5.6 km (18,000 ft) 90% below 16 km (52,000 ft) http://mychinaviews.com/2011/06/into-thin-air.html Drivers of atmospheric circulation Uneven solar heating At poles sun’s energy is spread over a larger region Uneven solar heating At poles sun’s energy is spread over a larger region Uneven solar heating At poles sun’s energy is spread over a larger region Ways to transfer heat Conduction: Transfer of heat by direct contact. Heat goes from warmer areas to colder areas. Ways to transfer heat Radiation: Any object radiates heat as electromagnetic radiation (light, infrared) based on temperature of the object. Ways to transfer heat Convection: Heat carried by a fluid (air, water, etc) from a region of high temperature to a region of lower temperature. Convection cell Warm air rises, then as it cools it sinks back down Thermal (heat) balance Heat in = Heat out, for earth as a whole ! Heat in = Heat out, for latitude bands " Heat out t r o p s n a r Heat in t t a e h t e N RedistributionIncreasing heat of heat drive atmospheric circulation So, might expect Cool air sinking near the poles Warm air rising at equator Lutgens and Tarbuk, 2001 http://www.ux1.eiu.edu/~cfjps/1400/circulation.html Turns out a 3 cell modelis better Polar cell Ferrel cell (Mid-latitude
    [Show full text]
  • Convection in a Volatile Nitrogen-Ice-Rich Layer Drives Pluto's Geological Vigour
    LETTER doi:10.1038/nature18289 Convection in a volatile nitrogen-ice-rich layer drives Pluto’s geological vigour William B. McKinnon1, Francis Nimmo2, Teresa Wong1, Paul M. Schenk3, Oliver L. White4, J. H. Roberts5, J. M. Moore4, J. R. Spencer6, A. D. Howard7, O. M. Umurhan4, S. A. Stern6, H. A. Weaver5, C. B. Olkin6, L. A. Young6, K. E. Smith4 & the New Horizons Geology, Geophysics and Imaging Theme Team* The vast, deep, volatile-ice-filled basin informally named Sputnik of pits in southern SP are evidence for the lateral, advective flow of Planum is central to Pluto’s vigorous geological activity1,2. SP ices1,2. Composed of molecular nitrogen, methane, and carbon monoxide From New Horizons spectroscopic mapping, N2, CH4 and CO ice all ices3, but dominated by nitrogen ice, this layer is organized into concentrate within Sputnik Planum3. All three ices are mechanically cells or polygons, typically about 10 to 40 kilometres across, that weak, van der Waals bonded molecular solids and are not expected to resemble the surface manifestation of solid-state convection1,2. Here be able to support appreciable surface topography over any great length we report, on the basis of available rheological measurements4, of geological time4,8–10, even at the present surface ice temperature of that solid layers of nitrogen ice with a thickness in excess of about Pluto (37 K)1. This is consistent with the overall smoothness of SP over one kilometre should undergo convection for estimated present- hundreds of kilometres (Fig. 1b). Convective overturn that reaches the day heat-flow conditions on Pluto.
    [Show full text]
  • Thermal Convection with a Freely Moving Top Boundary
    PHYSICS OF FLUIDS 17, 115105 ͑2005͒ Thermal convection with a freely moving top boundary Jin-Qiang Zhong Department of Physics, New York University, 4 Washington Place, New York, New York 10003 ͒ Jun Zhanga Department of Physics, New York University, 4 Washington Place, New York, New York 10003 and Applied Mathematics Laboratory, Courant Institute, New York University, 251 Mercer Street, New York, New York 10012 ͑Received 8 May 2005; accepted 29 September 2005; published online 22 November 2005͒ In thermal convection, coherent flow structures emerge at high Rayleigh numbers as a result of intrinsic hydrodynamic instability and self-organization. They range from small-scale thermal plumes that are produced near both the top and the bottom boundaries to large-scale circulations across the entire convective volume. These flow structures exert viscous forces upon any boundary. Such forces will affect a boundary which is free to deform or change position. In our experiment, we study the dynamics of a free boundary that floats on the upper surface of a convective fluid. This seemingly passive boundary is subjected solely to viscous stress underneath. However, the boundary thermally insulates the fluid, modifying the bulk flow. As a consequence, the interaction between the free boundary and the convective flow results in a regular oscillation. We report here some aspects of the fluid dynamics and discuss possible links between our experiment and continental drift. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2131924͔ I. INTRODUCTION cally active. The temperature difference between the hot in- terior and the cooler surface drives their mantle layers. As a When an upward heat flux passes through a fluid, the result, mantle convection ultimately drives all geological thermal energy is transported in two ways: conduction and events, such as volcanoes, earthquakes, and plate tectonics.8 convection.
    [Show full text]
  • Thunderstorms
    Thunderstorms Dana Desonie, Ph.D. Say Thanks to the Authors Click http://www.ck12.org/saythanks (No sign in required) AUTHOR Dana Desonie, Ph.D. To access a customizable version of this book, as well as other interactive content, visit www.ck12.org CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the FlexBook®, CK-12 intends to pioneer the generation and distribution of high-quality educational content that will serve both as core text as well as provide an adaptive environment for learning, powered through the FlexBook Platform®. Copyright © 2015 CK-12 Foundation, www.ck12.org The names “CK-12” and “CK12” and associated logos and the terms “FlexBook®” and “FlexBook Platform®” (collectively “CK-12 Marks”) are trademarks and service marks of CK-12 Foundation and are protected by federal, state, and international laws. Any form of reproduction of this book in any format or medium, in whole or in sections must include the referral attribution link http://www.ck12.org/saythanks (placed in a visible location) in addition to the following terms. Except as otherwise noted, all CK-12 Content (including CK-12 Curriculum Material) is made available to Users in accordance with the Creative Commons Attribution-Non-Commercial 3.0 Unported (CC BY-NC 3.0) License (http://creativecommons.org/ licenses/by-nc/3.0/), as amended and updated by Creative Com- mons from time to time (the “CC License”), which is incorporated herein by this reference.
    [Show full text]
  • Theoretical Study of the High-Latitude Ionosphere's Response to Multicell Convection Patterns
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 92, NO. A8, PAGES 8733- 8744, AUGUST 1, 1987 Theoretical Study of the High-Latitude Ionosphere's Response to Multicell Convection Patterns J. J. SOJKA AND R. W. SCHUNK Center for Atmospheric and Space Sciences, Utah State University, Logan It is well known that convection electric fields have an important effect on the ionosphere at high latitudes and that a quantitative understanding of their effect requires a knowledge of the plasma convection pattern. When the interplanetary magnetic field (IMF) is southward, plasma convection at F region altitudes displays a two-cell pattern with antisunward flow over the polar cap and return flow at lower latitudes. However, when the IMF is northward, mUltiple convection cells can exist, with both sunward flow and auroral precipitation (theta aurora) in the polar cap. The characteristic ionospheric signatures associated with multicell convection patterns were studied with the aid of a three-dimensional time-dependent iono­ spheric model. Two-, three-, and four-cell patterns were considered and the ionosphere's response was calculated for the same cross-tail potential and for solar maximum and winter conditions in the northern hemisphere. As expected, there are major distinguishing ionospheric features associated with the different convection patterns, particularly in the polar cap. For two-cell convection the antisunward flow of plasma from the dayside into the polar cap acts to maintain the densities in this region in winter. For four-cell convection, on the other hand, the two additional convection cells in the polar cap are in darkness most of the time, and the resulting 0+ decay acts to produce twin polar holes that are separated by a sun-aligned ridge of enhanced ionization due to theta aurora precipitation.
    [Show full text]
  • Chapter 13, Section 1: Thunderstorms
    Earth Science Identify the processes that form thunderstorms Compare and contrast different types of thunderstorms Describe the life cycle of a thunderstorm At any given moment, nearly 2000 thunderstorms are in progress around the world Both geography and air mass movements make thunderstorms most common in the southeastern United States For a thunderstorm to form, three conditions must exist A source of moisture For a thunderstorm to form, there must be an abundant source of moisture in the lower levels of the atmosphere Lifting of the air mass For a thunderstorm to form, there must be some mechanism for moisture to condense and release its latent heat This occurs when a warm air mass is lifted into a cooler region of the atmosphere An unstable atmosphere If the surrounding air remains cooler than the rising air mass, the unstable conditions can produce clouds that grow upward This releases more latent heat and allows continued lifting Because the rate of condensation diminishes with height, most cumulonimbus clouds are limited to about 12,000 m Thunderstorms are also limited by duration and size Thunderstorms are often classified according to the mechanism that causes the air mass that formed them to rise There are two main types of thunderstorms Air-mass Frontal When air rises because of unequal heating of Earth’s surface beneath one air mass, the thunderstorm is called an air-mass thunderstorm There are two kinds of air-mass thunderstorms Mountain thunderstorms Occurs when an air mass rises by orographic lifting
    [Show full text]
  • 1 Layers of the Atmosphere 1
    Atmosphere (Oceanography & Climate) Jesse Scheck Say Thanks to the Authors Click http://www.ck12.org/saythanks (No sign in required) www.ck12.org AUTHOR Jesse Scheck To access a customizable version of this book, as well as other interactive content, visit www.ck12.org CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the FlexBook®, CK-12 intends to pioneer the generation and distribution of high-quality educational content that will serve both as core text as well as provide an adaptive environment for learning, powered through the FlexBook Platform®. Copyright © 2013 CK-12 Foundation, www.ck12.org The names “CK-12” and “CK12” and associated logos and the terms “FlexBook®” and “FlexBook Platform®” (collectively “CK-12 Marks”) are trademarks and service marks of CK-12 Foundation and are protected by federal, state, and international laws. Any form of reproduction of this book in any format or medium, in whole or in sections must include the referral attribution link http://www.ck12.org/saythanks (placed in a visible location) in addition to the following terms. Except as otherwise noted, all CK-12 Content (including CK-12 Curriculum Material) is made available to Users in accordance with the Creative Commons Attribution-Non-Commercial 3.0 Unported (CC BY-NC 3.0) License (http://creativecommons.org/ licenses/by-nc/3.0/), as amended and updated by Creative Com- mons from time to time (the “CC License”), which is incorporated herein by this reference.
    [Show full text]
  • Introduction to Solar Physics
    Structure of lectures I Introduction and overview Core and interior: energy generation and standard solar model Introduction to Solar radiation and spectrum Solar Physics Solar spectrum Radiative transfer Sami K. Solanki Formation of absorption and emission lines Convection: The convection zone and IMPRS lectures granulation etc. January 2005 Solar oscillations and helioseismology Solar rotation Structure of lectures II Structure of lectures III: next time The solar atmosphere: structure Explosive and eruptive phenomena Photosphere Flares Chromosphere Transition Region CMEs Corona Explosive events Solar wind and heliosphere Sun-Earth connection The magnetic field CMEs and space weather Zeeman effect and Unno-Rachkovsky equations Longer term variability and climate Magnetic elements and sunspots Chromospheric and coronal magnetic field Solar-stellar connection The solar cycle Activity-rotation relationship Coronal heating Sunspots vs. starspots MHD equations & dynamo: see lectures by Ferriz Mas The Sun: a brief overview The Sun, our star The Sun is a normal star: middle aged (4.5 Gyr) main sequence star of spectral type G2 The Sun is a special star: it is the only star on which we can resolve the spatial scales on which fundamental processes take place. The Sun is a special star: it provides almost all the energy to the Earth The Sun is a special star: it provides us with a unique laboratory in which to learn about various branches of physics. 1 The Sun: Overview The Sun: a few numbers 30 Mass = 1.99 10 kg ( = 1 M) Average density = 1.4 g/cm3 26 Luminosity = 3.84 10 W ( = 1 L) Effective temperature = 5777 K (G2 V) Core temperature = 15 106 K Surface gravitational acceleration g = 274 m/s2 Age = 4.55 109 years (from meteorite isotopes) Radius = 6.96 105 km Distance = 1 AU = 1.496 (+/-0.025) 108 km 1 arc sec = 722±12 km on solar surface (elliptical Earth orbit) Rotation period = 27 days at equator (sidereal, i.e.
    [Show full text]
  • Atmospheric & Ocean Circulation
    Atmospheric & Ocean Circulation- Overview: Atmosphere & Climate • Atmospheric layers • Heating at different latitudes • Atmospheric convection cells (Hadley, Ferrel, Polar) • Coriolis Force • Generation of winds • Low pressure, wet, convergence • High pressure, dry, divergence • Climate zones Recall: Atmospheric temp. vs. height Heated from top: ozone absorbs energy Heated at the bottom: where the land is warm Atmospheric layers have different stability STRATOSPHERE: Stable because cool dense air is beneath warm dense air: STRATIFIED CONDITIONS ~19.9% of mass of atm TROPOSPHERE: Unstable because atmosphere is heated from below: CONVECTING CONDITIONS ~80% of mass of atm overall: TROPOSPHERE =the Weather Zone Also in TROPOSPHERE: CONVECTION due to heating from below STRATOSPHERE: STABLE because cool dense air is beneath warm dense air: STRATIFIED CONDITIONS STEPPING BACK: Fundamentally, Why does the Atmosphere circulate at all? What is energy source that sets it in motion? Oceanic motion ultimately derives from the Sun’s rays http://www.solarviews.com/raw/misc/ss.gif © Calvin J. Hamilton NASA http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question31.html Lights Please! Uneven solar heating with latitude • Solar energy in high latitudes: – Has a larger “footprint” – Is reflected to a greater extent – Passes through more atmosphere • Therefore, less solar energy per square meter is absorbed at high latitudes than at low latitudes Uneven solar heating with latitude another way to visualize: how “high” is sun in sky? Recall: basic radiation budget Reflected solar • Energy arrives as visible (shortwave) sunlight • About 30% is reflected “albedo” Earth • Higher reflection “albedo” at higher latitudes Incoming visible • The remainder leaves as outgoing infrared (longwave) radiation Outgoing infrared *+ GREENHOUSE GASSES : In atm.
    [Show full text]
  • Convection of Moist Saturated Air: Analytical Study
    atmosphere Article Convection of Moist Saturated Air: Analytical Study Robert Zakinyan, Arthur Zakinyan *, Roman Ryzhkov and Kristina Avanesyan Received: 29 October 2015; Accepted: 30 December 2015; Published: 5 January 2016 Academic Editor: Robert W. Talbot Department of General and Theoretical Physics, Institute of Mathematics and Natural Sciences, North Caucasus Federal University, 1 Pushkin Street, Stavropol 355009, Russia; [email protected] (R.Z.); [email protected] (R.R.); [email protected] (K.A.) * Correspondence: [email protected]; Tel.: +7-918-7630-710 Abstract: In the present work, the steady-state stationary thermal convection of moist saturated air in a lower atmosphere has been studied theoretically. Thermal convection was considered without accounting for the Coriolis force, and with only the vertical temperature gradient. The analytical solution of geophysical fluid dynamics equations, which generalizes the formulation of the moist convection problem, is obtained in the two-dimensional case. The stream function is derived in the Boussinesq approximation with velocity divergence taken as zero. It has been shown that the stream function is asymmetrical in vertical direction contrary to the dry and moist unsaturated air convection. It has been demonstrated that the convection in moist atmosphere strongly depends on the vapor mass fraction gradient. Keywords: thermal convection; Rayleigh–Benard convection; moist air; stream function; analytical model 1. Introduction Atmospheric convection is involved in many of the central problems in meteorology and climate science [1,2]. Investigation and understanding of atmospheric convection is of great importance for the development and improvement of global weather and climate prediction [3,4]. Convection interacts with the larger-scale dynamics of planetary atmospheres in ways that remain poorly represented in global models [5,6].
    [Show full text]
  • Mantle Convection Encyclopedia of Solid Earth Geophysics, Harsh Gupta (Ed.), Springer
    Mantle convection Encyclopedia of Solid Earth Geophysics, Harsh Gupta (ed.), Springer David Bercovici Professor & Chair Department of Geology & Geophsyics Yale University New Haven, Connecticut 06520-8109, USA E-mail: [email protected] Tel: (203) 432-3168 Fax: (203) 432-3134 December 26, 2010 Encyclopedia of Solid Earth Geophysics Mantle Convection, David Bercovici MANTLE CONVECTION tic techniques paved the way for the discovery of sea-floor spreading [Hess, 1962; Vine and Synonyms Matthews, 1963] and the birth of the grand uni- fying theory of Plate Tectonics in the 1960s; Mantle dynamics. Mantle circulation. this consequently revived interest in mantle con- vection as the driving mechanism for plate mo- Definition tions [Runcorn, 1962a,b] as well as non-plate- tectonic volcanism such as the possible Hawai- Mantle convection: Thermal convection in the ian plume [Morgan, 1971]. The success of man- terrestrial planetary mantles, the rocky layer be- tle convection theory in explaining plate veloc- tween crust and core, in which hot material rises, ities, sea-floor subsidence, volcanism, gravity cold material sinks and the induced flow governs anomalies, etc., lead to its further application to plate tectonic and volcanic activity, as well as other terrestrial planets such as Venus and Mars, chemical segregation and cooling of the entire which also sustained unique forms of mantle planet. convection, evident from volcanic activity. Mantle convection Basics of thermal or free convection Introduction and History Rayleigh-Benard´ Convection All planetary bodies retain some heat from their The simplest form of thermal convection is early formation but are inexorably cooling to referred to as B´enard convection named after space.
    [Show full text]
  • Cellular Cumulus Convection in a Moist Atmospheric Layer Heated Below*
    A ugust 1968 Tomio Asai 301 Cellular Cumulus Convection in a Moist Atmospheric Layer Heated Below* By Tomb Asai Geophysical Institute and Meteorological Research Institute, Kyoto University, Kyoto (Manuscript received30 January 1968, in revisedform 27 April 1968) Abstract The cumulus model proposed by Asai (1967) is applied to cellular cumulus convection in a moist atmospheric layer uniformly heated below and cooled above. The governing system of equa- tions derived has a steady state solution of cumulus convection independent of initial input distur- bances. A preferred mode of steady cumulus convection can be expressed in terms of an amount of heat supply, employing the selection principle that a preferred mode is one for which the lapse rate of temperature is the lowest. An examination of the results shows a coincidence with the feature of cumulus clouds in colder air over warmer water. However, tall vigorous cumulus convection is hardly expected to develop by uniform heating even with a large amount of heat supply. fragmental and little is known quantitatively of the 1. Introduction phenomenon described above. Further quantita- It has been well established that cellular convec- tive observations by aircrafts and meteorological tion, so-called Benard cell convection, takes satellites will be hopefully expected in the near place in a fluid layer heated below when the future to make clear characteristics of cumulus adverse temperature gradient exceeds a certain clouds and their distribution associated with en- critical value. This phenomenon has been con- vironmental conditions. firmed experimentally (Benard, 1900, etc) and An objective of the present article is to investi- theoretically (Rayleigh, 1916, etc.).
    [Show full text]