Meteorology Today An Introduction To Weather Climate And The Environment 13th Edition Pdf

[Vespasiano Jilg]

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Written by meteorologists C. Donald Ahrens and Robert Henson and grounded in the scientific method, Meteorology Today: An Introduction to Weather, Climate and the Environment, 13th edition, shows you how to observe, calculate and synthesize weather information as a scientist. Packed with engaging visuals, it provides the latest information on climate change, ozone depletion, air quality, El Nio and other key topics as well as discussions of recent high-profile weather events, including droughts, heat waves, tornado outbreaks and hurricanes. "Focus On" boxes help you delve deeper into meteorological observation methods and environmental issues, while case studies provide direct access to academic and newsworthy papers on recent developments. The MindTap for Meteorology digital platform includes concept check activities, animations and videos, and a variety of hands-on activities.

The objective of this work was to develop a system of acquisition of meteorological data in real time, using a programmable logic controller (PLC) as an alternative within the commercial weather stations. For sensing the air temperature, relative humidity, solar radiation, precipitation, wind speed and direction, commercial sensors were used during 2013, to test the station, in the meteorological station of the Graduate College, Campus Montecillo. The system consists of a PLC (CX1020 model, make Beckhoff), a laptop where an application for real-time monitoring that was developed in Visual Basic 2010 Express and the database MySQL was installed to store information, which can be used for several purposes. The interaction between the PLC and the application of monitoring was performed using wireless communication Wi-Fi. TwinCAT System Manager programs were used (for configuring the hardware) and TwinCAT PLC Control (for programming the PLC). The system operation was evaluated to make comparisons of sensor readings obtained against reference instruments and sensors of a meteorological station Campbell Scientific. The results indicate that it is feasible to use the PLC in the implementation of meteorological stations.

El objetivo de este trabajo fue desarrollar un sistema de adquisicin de datos meteorolgicos en tiempo real utilizando un controlador lgico programable (PLC) como una alternativa dentro de las estaciones meteorolgicas comerciales. Para sensar la: temperatura del aire, humedad relativa, radiacin solar, precipitacin, velocidad y direccin del viento, se usaron sensores comerciales, durante 2013, para probar la estacin, en la estacin meteorolgica del Colegio de Postgraduados, Campus Montecillo. El sistema se compone de un PLC (modelo CX1020, marca Beckhoff), una Laptop donde se instal una aplicacin de monitoreo en tiempo real que se desarroll en Visual Basic 2010 Express y la base de datos en MySQL para almacenar la informacin, que se puede usar para fines diversos. La interaccin entre el PLC y la aplicacin de monitoreo se realiz mediante comunicacin inalmbrica Wi-Fi. Se usaron los programas TwinCAT System Manager (para la configuracin del hardware) y TwinCAT PLC Control (para la programacin del PLC). Se evalu el funcionamiento del sistema al realizar comparaciones de las lecturas obtenidas de los sensores, contra instrumentos de referencia y sensores de una estacin meteorolgica Campbell Scientific. Los resultados indican que es factible el uso del PLC en la implementacin de estaciones meteorolgicas.

Climate and weather directly affect the environment of the human being, involved in various aspects such as biological, social and economic. On the one hand, climate allows to know the long-term average of the elements of weather, and the latter in turn, allows to know the atmospheric behaviour in the short term (one to several days). Hence, the importance of studying to have representative information that could help in the development of various activities such as urban development, agriculture, transportation, health, recreation, prevention of disasters, weather, global warming and climate change , among others.

Some basic concepts are defined, for example according to Ahrens et al. (2012), meteorology (Greek meteors "high in the sky" and logos "study" is the interdisciplinary science for studying weather, the atmospheric environment, the phenomena produced there and the laws that govern it, and which uses the weather station as an instrument for measuring the weather elements. The World Meteorological Organization (WMO) defines a weather element as an atmospheric variable or phenomenon that characterizes the weather in a specific place and at any certain time (air temperature, pressure, wind, humidity, storms, fog, cyclones and anticyclones, etc.). The temperature is defined as a physical quantity that characterizes the movement of molecules through a body (WMO, 1992).

The relative humidity as "the reason expressed in percentage, between the observed pressure steam saturation voltage at the same temperature and pressure steam" (WMO, 1998). The precipitation as liquid or solid condensation of water vapuor falling from clouds or the air and deposited on the ground product includes snow, sleet, rain mist and dew (WMO, 2008).

Solar radiation is the energy in the form of electromagnetic waves from the sun and the earth receives. Atmospheric pressure is the force exerted per unit area, as a result of the weight of the atmosphere above the measuring point (WMO, 2008). Mozarrela (1972) defined the wind like a three-dimensional vector quantity with small random fluctuations in space and time, superimposed on a larger scale organized flow, and secondly Gnter (2002) defines it as "the compensation of differences in atmospheric pressure between two points".

In Mexico, it mainly depends on meteorological stations of foreign manufacturing, making it necessary to develop competitive systems taking advantage of new technologies and thus have the ability to develop and implement new requirements, with the PLC one of those technological alternatives that were implemented in this paper.

Regarding functions that should have a weather station must have 1) meteorological sensors to provide an electronic signal; 2) electronics to convert the sensor signal to a digital value; 3) storage media for backup site; and 4) telecommunications hardware for data transmission, preferably (Tanner, 1990).

The programmable logic controller (PLC) is defined as a digitally operated electronic system designed for the use in an industrial environment, which uses a programmable memory for storing instructions to implement specific functions such as logic, sequence, timing, counting and arithmetic to control through inputs and outputs, digital or analogue, various types of machines or processes (NEMA, 2005). Typical components in a system PLC are: processor, memory, power supply section input/output communication interface, and the device programming (Boltn, 2009). Figure 1 shows the basic arrangement.

The PLC is able to work with both digital and analogue signals, with the first variable with two distinct levels representing the "false" and "true" logic states and that only the PLC's work with 0 V dc and 24 V dc respectively. Moreover the analogue signals are variables that vary with time in a manner analogous to a physical variable that carry information and include physical quantities such as voltage, current and intensity (Ambardar, 2002).

Regarding the classification of the PLC's stand mainly two criteria, the first criterions is according to their structure, divided into compact and modular, where the compact has all elements integrated into a main module, while the modular contains your items individually and together make up the controller. The second criterion for classification is according to its processing power. They are classified into low, medium and high end, where the low range comprises a maximum of 128 inputs/outputs and up to 4K instruction; the average range comprises a maximum of 512 inputs/outputs and up to 16 K instructions; and finally high-end, that supports more than 512 inputs/outputs and 16K instructions (Pea, 2003). According to these criteria, the CX1020 PLC that was used in this project is the modular high-end and according to their characteristics (Beckhoff, 2013).

For the design and construction of the acquisition system, we used a programmable logic controller (PLC - Programmer Logic Controller) CX1020 and digital and analogue input modules Beckhoff brand; power supply 24 Vdc, Weidmller brand; solar radiation sensor LI-200 model brand LICOR; Sensor of air temperature and relative humidity, HO2NVSTA1 model, Veris brand; Campbell Scientific TE525 gauge mark; speed sensor Model 03101 and Model 03301 wind direction wind sensor, both Campbell Scientific brand.

We built a slotted aluminium structure, on which the meteorological sensors and control cabinet with IP65 water protection were mounted (according to IEC 60529, 2001-2002). Inside the cabinet, the components were installed: PLC, power supply, digital and analogue cards inputs, thermo-magnetic switch and some other ancillary components, such as terminals, din rail for mounting elements, channelling chute for wiring and connectors for outer wires (Figure 2 and 3).

The EtherCAT, which is a protocol that uses a "EtherType" officially assigned within the frame of Ethernet (EtherCAT, 2013), which works on Ethernet networks and where the EtherType is used for communication between the PLC and input modules, in a field of two octets within the Ethernet frame that is used to indicate the nature of the client protocol (IEEE 802.3, 2005). Also with a wireless access point, TP-Link for a remote connection from a central computer, where an application for real-time monitoring of values read it ran and that has a MySQL database for storage and later reference (Figure 4).

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