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Advances in Astronomy The Solar Cycle Guest Editors: J. Javaraiah, J. P. Rozelot, and Luca Bertello The Solar Cycle Advances in Astronomy The Solar Cycle Guest Editors: J. Javaraiah, J. P. Rozelot, and Luca Bertello Copyright © 2012 Hindawi Publishing Corporation. All rights reserved. This is a special issue published in “Advances in Astronomy.” All articles are open access articles distributed under the Creative Com- mons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Editorial Board Cesare Barbieri, Italy Martin Hardcastle, UK Valery Nakariakov, UK Joshua S. Bloom, USA Dean Hines, USA Jerome Orosz, USA Michael Brotherton, USA Dieter Horns, Germany George Pavlov, USA Giovanni Carraro, Italy Ivan Hubeny, USA Juri Poutanen, Finland Alberto J. Castro-Tirado, Spain John Hughes, USA Somak Raychaudhury, UK Michael Disney, UK Wing Huen Ip, Taiwan William Reach, USA Elmetwally Elabbasy, Egypt Valentina Klochkova, Russia Peter Roming, USA Nye Evans, UK Gregory Laughlin, USA Ata Sarajedini, USA Maurizio Falanga, Switzerland Myung G. Lee, Republic of Korea Regina Schulte-Ladbeck, USA Duncan Forbes, Australia Karen Leighly, USA Ravi Sheth, USA Andrew Fruchter, USA Jeffrey Linsky, USA Roberto Turolla, Italy B. T. Gansicke,¨ UK Mario Mateo, USA Gary Wegner, USA Paul Goldsmith, USA Ronald Mennickent, Chile Glenn J. White, UK Jonathan Grindlay, USA Zdzislaw E. Musielak, USA Paul J. Wiita, USA Contents The Solar Cycle,J.Javaraiah,J.P.Rozelot,andLucaBertello Volume 2012, Article ID 470631, 2 pages The Faint Young Sun Paradox: A Simplified Thermodynamic Approach, F. Angulo-Brown, MarcoA.Rosales,andM.A.Barranco-Jimenez´ Volume 2012, Article ID 478957, 10 pages Tendency of Discreteness of the Solar Amplitude and Intercycle Relatedness, Akio Yoshida and Ryan Sayre Volume 2012, Article ID 519852, 7 pages Rapid Disappearance of Penumbra-Like Features near a Flaring Polarity Inversion Line: The Hinode Observations, B. Ravindra and Sanjay Gosain Volume 2012, Article ID 735879, 9 pages Kinematic Approach to the 24th Solar Cycle Prediction, Vladimir Kaftan Volume 2012, Article ID 854867, 7 pages Probable Values of Current Solar Cycle Peak,V.M.Silbergleit Volume 2012, Article ID 167375, 6 pages Sunspot Cycle 24 and the Advent of Dalton-Like Minimum,H.S.AhluwaliaandR.C.Ygbuhay Volume 2012, Article ID 126516, 5 pages Preliminary Results on Irradiance Measurements from Lyra and Swap, S. T. Kumara, R. Kariyappa, M. Dominique, D. Berghmans, L. Dame,´ J. F. Hochedez, V. H. Doddamani, and Lakshmi Pradeep Chitta Volume 2012, Article ID 623709, 5 pages Observations of Correlated Behavior of Two Light Torsion Balances and a Paraconical Pendulum in Separate Locations during the Solar Eclipse of January 26th, 2009, A. F. Pugach and D. Olenici Volume 2012, Article ID 263818, 6 pages Hindawi Publishing Corporation Advances in Astronomy Volume 2012, Article ID 470631, 2 pages doi:10.1155/2012/470631 Editorial The Solar Cycle J. Javaraiah,1 J. P. Rozelot,2 and Luca Bertello3 1 Sun and Solar System Group, Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034, India 2 Nice Sophia-Antipolis University, OCA-Lagrange, CNRS UMR 7293, Boulevard de l’Observatoire, BP 4229, 06304 Nice Cedex 4, France 3 National Solar Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719, USA Correspondence should be addressed to J. Javaraiah, [email protected] Received 28 June 2012; Accepted 28 June 2012 Copyright © 2012 J. Javaraiah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Sun provides variable energetic and magnetic field input solar flares and coronal mass ejections pose a serious hazard to the conditions in the heliosphere which directly affect the to astronauts, satellites, polar air traffic, electric power magnetosphere. In particular, the Sun’s variable magnetic grids, and telecommunications facilities on short time-scales fields constitute a rich source for processes that influence ranging from hours to days, the solar radiative output the Earth’s upper atmosphere and geomagnetism. The Sun affects planetary and global climate on much longer time- follows a periodic cycle of activity. This cycle, called the solar scales (from decades to stellar evolutionary time-scales). We cycle, has its evident manifestation by the periodic recurrence refer the readers to the recent review by David H. Hath- of sunspots, or darker, relatively cool and strong magnetic away (solarphysics. livingreviews.org/Articles/lrsp-2010-1/) regions at the Sun surface. This periodicity was discovered for more information on the solar cycle. first by Samuel Heinrich Schwabe in 1844 when he observed During the last few decades, technological advances have the variation of the number of sunspots over a seventeen- led to the acquisition of a huge amount of high-quality data year period. The solar cycle usually lasts about eleven years on solar magnetic field and solar activity. The development on the average, and there is little doubt that it is magnetic in of helioseismology, the technique of studying solar interior nature and produced by dynamo processes within the Sun. It through the study of its global oscillations, has led to is believed that the 11-year solar cycle results from generation spectacular success in determining Sun’s internal structure of strong toroidal magnetic fields in the Sun, with a main and rotation with increasing accuracy. period of about 22-years, by combined effects of convection We invited authors to contribute this special issue of the and differential rotation in the Sun. journal original research articles as well as review articles that Although most of the characteristics of the solar cycle can stimulate the continuing efforts to understand the solar have been investigated for many years, we still do not cycle and its impact on space weather and global climate. know exactly what causes the 11-year solar cycle. This is Eleven original research articles were received. All these were one of the most important unsolved problems in solar peer-reviewed by a minimum of two referees. Eight of them physics today. Because of the long record of observations, accepted for publications in this special issue. In three of sunspot measurements still constitute a primary source of the papers the predictions for the amplitude and duration of information to better understand the level and nature of solar cycle 24 were presented, mainly from the statistical analyzes activity. Statistical and morphological studies of sunspots of the sunspot data, and in five papers research on basic have significantly improved our knowledge of this field. property of solar cycle and related topics were presented. Other solar activity indicators including the 10.7 cm radio We hope that students and researchers will find this flux, the total and spectral solar irradiance, the magnetic special issue useful. Since the Advance in Astronomy is an field, flares and coronal mass ejections, geomagnetic activity, open-access journal, all of the papers of this special issue are and galactic cosmic ray fluxes have also shown temporal accessible free of charge to anyone with a computer and an properties related to the solar magnetic activity cycle. While Internet connection. 2 Advances in Astronomy Acknowledgments We sincerely thank the authors and referees of the articles submitted to this special issue. We are also thankful to the members of the editorial board of Advances in Astronomy, Hindawi publisher. Without their support and hard work, this special issue would not have come into being. J. Javaraiah J. P. Rozelot Luca Bertello Hindawi Publishing Corporation Advances in Astronomy Volume 2012, Article ID 478957, 10 pages doi:10.1155/2012/478957 Research Article The Faint Young Sun Paradox: A Simplified Thermodynamic Approach F. Angulo-Brown,1 Marco A. Rosales,1 and M. A. Barranco-Jimenez´ 2 1 Departamento de F´ısica, Escuela Superior de F´ısica y Matematicas,´ Instituto Polit´ecnico Nacional, UP Zacatenco, 07738 Mexico, DF, Mexico 2 Departamento de Formacion´ Basica,´ Escuela Superior de Computo,´ Instituto Polit´ecnico Nacional, Avenida Juan de Dios Batiz s/n. Esquina M. Othon´ de Mendizabal UP Adolfo Lopez´ Mateos, 07738 Mexico, DF, Mexico Correspondence should be addressed to M. A. Barranco-Jimenez,´ [email protected] Received 15 December 2011; Revised 16 March 2012; Accepted 15 May 2012 Academic Editor: J. P. Rozelot Copyright © 2012 F. Angulo-Brown et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Classical models of the Sun suggest that the energy output in the early stage of its evolution was 30 percent less than today. In this context, radiative balance alone between The Sun and the Earth was not sufficient to explain the early presence of liquid water on Earth’s surface. This difficulty is called the faint young Sun paradox. Many proposals have been published to solve this paradox. In the present work, we propose an oversimplified finite-time thermodynamic approach that describes the air convective cells in the Earth atmosphere. This model introduces two atmospheric modes of thermodynamic performance: a first mode consisting in the maximization of the power output of the convective cells (maximum power regime) and a second mode that consists in maximizing a functional representing a good trade-off between power output and entropy production (the ecological regime). Within the assumptions of this oversimplified model, we present different scenarios of albedo and greenhouse effects that seem realistic to preserve liquid water on the Earth in the early stage of formation. 1. Introduction to reconcile these facts. Among the evidence for ancient liquid water temperatures at the Earth’s surface is the dating The so-called faint young Sun paradox [1]isakeydrawback of sedimentary rocks, that is, rocks laid down under water.