Meteorological Principles and Concepts
A Scientific theory provides a vivid explanation of various aspects of the natural world (Suppe 32). It uses substantial facts that have undergone confirmation through numerous experimentation and observations. The hypothesis of the natural world, on the other hand, argues that the explanation of the world lies not in science but in forces outside the natural world – probably a supreme being (Veizer 212).
Weather is a term used to define the atmospheric state. Basically, it describes the day-to-day atmospheric activities such as temperature changes and precipitation. It only presents the present conditions. On the other hand, climate provides measurements of atmospheric conditions over a long period. Such conditions include those of the atmospheric pressure, precipitation, temperature and humidity.
The four spheres of the earth include the lithosphere, hydrosphere, biosphere and the atmosphere (Schopf 322). All these spheres are interconnected. The lithosphere is made up of the earth’s surface material, the semi-solid material beneath the surface and the molten rock towards the centre of the earth. The hydrosphere is the part of the earth that contains water in all its forms. The biosphere is the area of the earth that contains living things. The atmosphere contains the earth’s air.
The sun is the external source of the earth’s energy. This comes in the form of solar energy. Internal energy sources include the earth’s gravitational energy. Energy is also generated through the decay of radioactive isotopes within the earth.
The atmosphere is the region of the earth that is composed of the gases that surround it and provide possibility of life. The gases are held towards the surface by gravity. This layer absorbs ultraviolet solar energy from the sun and maintains the temperatures of the earth at levels that enable the survival of species.
Heating of the earth’s atmosphere and surface
The earth’s rotation is the movement of the body around its own axis. The solid earth moves from the west towards the east. This is what makes the day and night. The revolution of the earth is the movement of the body around the sun on its orbit. This takes about 366 days.
The solar energy that reaches the earth’s surface depends on the variations in angular position of the sun’s rays reaching that specific point. The change in the angle of solar radiation will determine the thickness of the atmosphere that will need to be penetrated. The significant days based on these variations are the summer solstice, winter solstice, autumnal equinox and spring equinox.
The three mechanisms of energy transfer on the earth are radiation, conduction and convection. Radiation is the transfer of energy through electromagnetic waves (Reitz, Milford, and Christy 211). Conduction is through a medium while convection is through air or fluid.
Electromagnetic radiation is a type of energy. It is emitted by charged particles. They move in such a way as to resemble a wave. It has both an electric and magnetic field moving perpendicular to each other.
The earth’s heat budget is displayed by the balance between the incoming energy and outgoing energy such that both are equal. Heat may be transferred from lower latitudes to higher latitudes in order to maintain this balance.
The role of temperature on weather and climate
The degree of temperature determines whether the weather is sunny or rainy because it affects the amount of precipitation. Temperature also determine seasons such as winter and summer.
The earth is divided into the northern hemisphere and southern hemisphere. The latitudes determine the angle at which the sun’s rays hit the surface and consequently the amount of temperature on the surface. The areas around the equator are hottest while those further are cooler.
The latitudinal shifts in temperature are explained by the geographic variations caused by the shape of the earth (spherical shape of the earth). It causes changes in the angle of incident solar radiation. In July, the temperatures are higher over continents than over oceans in the Northern Hemisphere (Windley 210). In the Southern Hemisphere, the opposite is true. Local variations in temperature are facilitated by the wind temperatures and the oceanic currents.
The solar intensity in the Northern and Southern Hemispheres vary during seasons such as winter and summer. The Northern Hemisphere leans towards the sun during summer and away during winter. The opposite is true with the Southern Hemisphere. The part of the earth that leans towards the sun at a particular season receives more solar energy. There are several applications of temperature data. This information could be used to predict weather conditions and seasonal changes (Weart 54).
Definitions of terms
Albedo – this is the reflective power of the surface.
Isotherms – these are lines that connect areas of the earth that have the same temperature at a particular time.
Kelvin scale – this is a temperature scale that has an absolute zero. Below zero, temperatures do not exist.
Fahrenheit scale – this is a scale divided into 180 equal intervals. It shows the difference between the boiling and melting points of water.
Celsius scale – this is a scale that divides the interval between the freezing and boiling points into 100 equal intervals.
Thermometer – this is a device used to measure temperature.
The role of moisture in atmospheric stability
The hydrologic cycle describes the movement of water on the surface, below and above it in its different states. Water vapour is water in gaseous state.
Humidity defines the amount of vapour in the air. A hygrometer is used to measure the amount of water vapour. In contrast to humidity, relative humidity describes the amount of vapour in relation to that which is available in a mixture of air and water vapour.
Below a specific temperature at constant pressure, water vapour condenses into a liquid state. This temperature is referred to as the dew point. A psychometer is used to measure relative humidity. It consists of a wet bulb and a dry bulb. As water in the wet bulb evaporates, temperature on both bulbs is read this helps provide the relative humidity. Adiabatic temperature changes occur when air molecules try to spread out due to low atmospheric pressure. Since it requires energy to spread out, they vibrate slowly and as a result lead to a drop in temperature. The mechanisms that cause air to rise include orographic lift, convergence, convective lift and frontal lift.
As water heats up, it evaporates and goes up in the air as water vapour. It then mixes with dust particles and forms clouds. It may then come back down in form of precipitation. Air is said to be stable when the weather is generally calm. This calmness is also observed during precipitation. Factors that cause instability include adiabatic and environmental lapse rates.
Condensation and precipitation
Condensation is the change of a gas into a liquid. This occurs when the temperatures of the gas drops to levels that cause it change in form. This may also occur when a gas is compressed to its saturation limit. Clouds are visible masses of water droplets suspended over the earth’s surface.
They may be classified by their height and appearance (texture). The major cloud forms include appearance as a curl, layer or heap. The basic cloud types include cirrus clouds, stratus, cumulus, nimbus, cirrocumulus, cirrostratus, altocumulus, altostratus, nimbostratus, stratocumulus and cumulonimbus.
Fog consists of water droplets that are either suspended near the surface of the earth or at the surface. The mechanism of formation is condensation where water vapour condenses to form water droplets. Precipitation is what falls down through gravity as a result of condensed material in the air. They include rain and snow. Others include sleet, graupel and hail.
The instrument used for measuring precipitation is the rain gauge. This measures units less than a hundredth of an inch. Weather modifications include the intentional manipulation of weather. Cloud seeding is one form and it is used to increase precipitation. Storm prevention is another form of modification meant to reduce incidences of storm. Failures include destruction of the ecosystem, accidents and health risks.
Air pressure and the resultant winds
Air pressure is the force that air exerts on the earth’s surface. It is the force per unit area of the surface. The unit of measuring pressure is pascal (Pa). The instrument used for measurement is the manometer. Pressure decreases with the increase in altitude. This is because of the decrease in the number of air molecules with the increase in height.
Factors that determine amount of air pressure on a mass of calm air include the temperature, the specific gravity of the area and the presence or absence of moisture in the air. As the sun heats the surface of the earth, the air heated and as it warm, it rises. This causes a change in pressure and the air in high-pressure move towards the areas of lower pressure. This movement is shown in form of wind. Wind is controlled by windbreakers such as trees.
The coriolis effect is the force acting on a body (such as air) that is in motion. It occurs in a system (earth) that is in rotation. It affects wind in that it causes the formation of flow around the low-pressure areas. It also acts to sustain that flow. Isobars are lines in a map connecting areas of equal pressure. The distribution of the isobars is used to describe pressure changes in that they are related to the magnitude and direction of wind. The nature of the surface of the earth determines the speed and direction of wind. Presence of hills and forest, for example, will cause winds to be slower and change direction.
Cyclone formation begins with warm, moist air rising over the ocean and causes a lower air pressure below. Surrounding air rushes into the area of low pressure. The warm air above cools and forms clouds. This process repeats and rotates faster causing an eye to form and hence a cyclone. Wind may be measured using an anemometer (rotation of rotating cups) or by the propagation speed of ultrasound signals. The latter is used for higher accuracy.
Circulation of the atmosphere
Macroscale winds are the largest wind patterns (planetary-scale). Mesoscale winds are smaller-scale winds such as tornados and thunderstoms (Rasmussen and Turner 23). A tornado is a large column of violently rotating air. It is usually in contact with both the surface and the clouds. Microscale winds are the smallest winds (Maddox 55). All winds are caused due to pressure changes.
The three-cell circulation model describes the earth’s general circulation. The cells include Hadley, polar and ferrel cells. The two latitudinally oriented belts of high pressure include the polar high and subtropical high. The two belts of low pressure include the sub-polar low and equatorial low. The greatest seasonal change in earth’s global circulation develops into monsoons (Maddox, Howard, and Rogers 98).
Rossby waves are huge undulations at a horizontal plane in the atmosphere. They separate the cold polar air from the warmer tropical air. El Nino is the abnormal warming of surface ocean waters while La Nina is the cooling of the ocean surface to temperatures below the usual levels. Global precipitation patterns may be altered by global warming, which is the rise in the atmospheric temperatures.
Air masses and weather patterns
Air masses are volumes of air. They are usually defined by their temperature and water vapour content. Windy conditions usually accompany air-mass weather. Source regions are areas where air masses originate (Inoue, Kawashima, and Fujiyoshi 78). For a source region to be considered ideal it must meet two criteria. The first is that the area must be extensive and physically uniform. The other is that the air must have some certain level of stagnation.
Air masses are classified according to the thermal characteristics, the moisture properties and the atmospheric stability of the source. The first letter denotes the moisture properties of the source region. The second one describes the thermal characteristics of the area. The last letter describes the atmospheric stability.
As air masses move from origin, they encounter changes in stability. Factors that may changes in stability include surface flux from vegetations growing below, heat from underlying waters (Freeman and Fitzjarrald 102). The main characteristics of air masses that influence the daily weather patterns include temperature and water vapour content. They determine precipitation and other related weather conditions.
A Nor’easter is a type of storm travelling from the south to the northeast. It is similar to a hurricane. Most of the stormy weather experienced in the United States is caused by the middle latitude cyclones. This can be described as an area of low pressure. It is usually located between 30 and 60 degrees latitude (Spiegler 380).
A front is a zone where two types of air masses meet (transition). The different types of fronts include the cold front, the warm front, the stationary front and occluded front. They are characterised by sharp changes in temperature, changes in moisture content, shifts in wind directions and low-pressure troughs.
The polar front model describes the transitional region separating the warm air from the tropics and the cooler air from the poles in the middle latitudes. The strong temperature gradient causes the conversion of the potential energy into kinetic energy. This is associated with the mid-latitude cyclones.
Airflow aloft helps in maintaining cyclones and anti-cyclones since they create areas of low pressure and areas of high pressure. an anti-cyclone portrays characteristics opposite to that of a cyclone. Their central air pressures are higher than that of their surroundings. They are also characterized by subsiding air.
Cyclonic activities in North America vary with seasons. During winter, the depressions increase chances for the formation of tropical cyclones (anti-cyclonic activity). During spring, the cyclonic activity in North America are characterised by cyclonic activity.
Thunderstorms, tornados and hurricanes
A cyclone is an area where a body of water is flowing in a circular motion and in directions similar to that of the earth. The formation of thunderstorm is described in three distinct stages. The first stage is the cumulus stage. This is whereby the sun heats the surface. The warm air rises and may form cumulus clouds.
The next stage is the mature stage. This is whereby the clouds become enlarged such that precipitations start to occur. The last stage is the dissipating stage. This occurs after about thirty minutes. This forms when the cloud droplets can form no more. Light rains may occur as the clouds disappear.
There are normally more thunderstorms during summer than during winter because of the differences in temperature. The sun hits the surface more during summer allowing the process to occur. The attributes of a strong thunderstorm is the temperature and humidity. When the air is hotter and has more water, (vapour) the thunderstorm would be more severe. A squall line usually forms along or in front of a cold front.
A mesoscale convective complex may be defined through satellite imagery. They are mainly the result of the merging of thunderstorms into a small squall line. Tornados originate from severe thunderstorms (Maddox 1380). These thunderstorms last longer than the usual ones. As the wind gets into the storm, swirling begins forming a funnel shape. The high speeds create a low pressure inside the funnel causing a vacuum effect thus sucking things inside.
A Doppler radar is used to measure velocities. It sends radio waves that are reflected back by the object in air. This may be used to predict storms (tornados) and their intensities. Hurricanes are formed as heated water vapour rises and twists high in the atmosphere. As the winds begin to circle, it forms an eye. The hurricane is powered by more moisture from the sea. The Saffir-Simpson Scale is used in the classification of US hurricanes. This classification is based on the intensity of the sustained winds.
Factors that can cause the decrease in the intensity of a hurricane include the reduction in the amount of moisture. This occurs as the hurricane approaches dry land. A warning means that a particular phenomenon or condition is ongoing. On the other hand, a watch means that the phenomenon is likely to happen because of the conducive conditions. Key factors in determining a watch is the increased risk of hazardous weather conditions. Factors determining a warning include the presence of hazardous weather conditions.
Overview of meteorology and how it affects my career
Meteorology is the study of the atmosphere. This includes the observation of the weather events in the atmosphere. These events are explained by the science of meteorology. The field of study is significant for my career as a Navy Reserve Operational Meteorologist.
Having been an Assistant Forecaster and Educator, I was able to come across some of the concepts in meteorology especially during meteorological and oceanographic functions that I performed. Other subjects that relate to meteorology include Planetary Science, Atmospheric Physics and Physical geography. I developed and taught these subjects during the course of my career.
This subject also adds value to the vast information I received during my training on Naval Meteorology and Oceanography Community. I believe this subject would also have a positive impact towards my Navy Reserve Weather Forecasting Qualification.
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Freeman, Jeffrey and David Fitzjarrald. “Postfrontal airmass modification.” Journal of Hydrometeorology 1.1 (2009): 419-437. Print.
Maddox, Ray. “Mesoscale convective complexes.” Bulletin of the American Meteorological Society 61.1 (1980): 1374-1387. Print.
Maddox, Ray, Wallace Howard, and Daniel Rogers. Mesoscale convective compexes in the middle latitudes. Boston: American Meteorological Society, 1986. Print.
Rasmussen, Erik and John Turner. Polar lows: Mesoscale weather systems in the polar regions. Cambridge: Cambridge University Press, 2003. Print.
Reitz, John, Fredrick Milford, and Robert Christy. Foundations of electromagnetic theory. New York: Addison Wesley, 1992. Print.
Schopf, John. Earth’s earliest biosphere: Its origin and evolution. Princeton: Princeton University Press, 1983. Print.
Spiegler, David. “Reply.” Monthly Weather Review 101.4 (1973): 380. Print.
Suppe, Frederick. The structure of scientific theories. New York: Sage, 1977. Print.
Veizer, Brandon. The early history of the earth. London: John Wiley and Sons, 1976. Print.
Weart, Spencer. The modern temperature trend. New York, 2007. Print.
Windley, Bob. The Evoluting continents. New York: Wiley Press, 1984. Print.
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