Gas Behaviours and the Weather

8090171

Gas Behaviour and the Weather

The atmosphere above the Earth’s surface consists of a mixture of gases called air. By learning about the nature, concepts and laws of gases, the changes in the atmosphere can be monitored and future weather events can be predicted. The accuracy of these predictions however, is questionable as the gas laws are only accurate for ideal gases. The air in the atmosphere is not an ideal gas and therefore, there are many variables that must be taken into account when predicting and measuring temperature, pressure, volume, and density of the atmosphere’s air.

Pressure can be defined simply as the amount of force applied to a unit area of surface (Princeton University – WordNet, 2010). Air pressure is the weight of the air pressing down on Earth. Weight is the measure of the amount of force pushing down on Earth due to gravity. Therefore, measuring the weight of the air pressing down on Earth measures the amount of force applied to the Earth’s surface and thus, the pressure. Air pressure also relates to the density of the air and the height above the Earth’s surface from where it is being measured (see Passante, 2006). The lines on the weather map (Fig. 1) represent the variations in pressure from region to region shown in ‘isobars’.

Temperature is a measurement of the speed of the molecules’ movement in a substance. The more energy the molecules have, the faster they move and the higher the temperature is. When measuring the temperature of the air, it is the speed of the molecules that is being measured (Bureau of Meteorology, 2010).

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Temperature and pressure increase in ratio with each other. High temperatures close to the Earth are caused by high pressure systems. High pressure systems drive the higher air to cool and become denser so that as it sinks towards the Earth, it becomes warmer (see Passante, 2006). High pressure systems are more stable and larger than low pressure systems and last longer over large areas (see Passante, 2006). Therefore, a high pressure system means higher temperatures in the weather and generally clear and sunny skies. Low pressure systems cause the air to become warmer and less dense and therefore rise (see Passante, 2006). This means that the temperature on the Earth is cooler. High pressure regions can be simply defined as regions of sinking air. Low pressure regions can be defined as regions of rising air (Bureau of Meteorology, 2010).

When predicting future weather events, the concepts and laws relating to gases are very relevant. Prediction of rain can be made by monitoring the air pressure in a particular region (see Passante, 2006). If the pressure has a low measurement, it is very likely that precipitation will occur. In low pressure systems rain, clouds and strong winds often occur (see Passante, 2006). Wind occurs in regions with greater pressure differences and is the air passing from high to low pressure systems. In Fig. 2, the direction of air flow is displayed and it can be seen that pressure systems affect air flow. Outside of the tropics, the main wind flow is reliant on the distribution of atmospheric pressure (see Bureau of Meteorology, 2010). Prediction of weather for the general community is calculated using complicated grids and numerical processes which involve observations, variables and conditions of the particular region and physics to do with radiation which all has an effect on the weather (see dmi.dk, 2008). Thunderstorms and cyclones are predicted by observing and monitoring the atmospheric conditions. Thunderstorms generally form when there is moist, warm air in the lower regions of the atmosphere and dry and cool air in the higher parts of the atmosphere (see Passante, 2006).

The gas laws state, that if the initial pressure is increased, then the volume of the gas must decrease, and vice versa (see Stace-Winkles, 2010). This is apparent in Boyle’s Law (P1V1 = P2V2). Hence, the gas laws are helpful in understanding pressure systems and the weather. The increase and decrease of volume and the change in the density of the gas which causes air to rise or sink, is a fundamental aspect of the gas laws, as this occurs because of change in pressure in the different pressure systems (see Bureau of Meteorology, 2010). The gas laws also explain change in temperature in the weather. The Gay-Lussac Law (P1/T1 = P2/T2) states that as the pressure of a gas increases, the temperature must also increase. With increased pressure there is denser gas in an area and therefore more molecules of gas which means more energy and therefore higher temperature. In the weather accordingly, higher pressure regions mean higher temperatures and lower pressure regions mean lower temperatures (see Passante, 2006). However, the gas laws are laws that were created for ideal gases; gases that are hypothetical, with identical particles of zero volume and with no intermolecular forces (see Stace-Winkles, 2010). This means that when relating the gas laws to the weather and real gases in the environment, there will be many variables that will affect the accuracy of these laws. The variables are things like high pressure, which affects the attraction between particles and means that the volume can no longer be considered zero, and low temperature, which causes the particles to move closer to each other and therefore become more attracted to each other (see Stace-Winkles, 2010). Ideal gases also do not cater for different types of gases which could have larger and polar molecules (see Stace-Winkles, 2010). The laws explain the basics of how gases in the atmosphere behave but cannot provide perfectly accurate results when measuring pressure and temperature and basing weather predictions on these measurements.

Gas behaviour and the laws and concepts relating to gases, are imperative to understanding weather but can not be relied on to produce accurate weather predictions. The air in the atmosphere has so many variables and inconsistencies compared to ideal gases and therefore meteorological events are difficult to predict and are often inaccurate. By monitoring atmospheric conditions, future weather events can be predicted but the exact details and the probability of them actually occurring is inexact.

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pictureperfect

13th of Jul 2012

Quality of writing

I feel that this essay doesn’t flow as well as it could, the candidate jumps from point to point and their paragraphs are short and seem unrelated. This could be improved by changing the order of some of the paragraphs and ensuring that key points link together. It can be useful to write out a plan before you write your essay, this gives you a chance to work out what you want to say and how to link things together. On a more positive note, the candidate uses technical terms appropriately and there are issues with spelling or grammar.

Level of analysis

The candidate has stated resources they have used when researching this topic which is sensible. However they have done so my including parentheses throughout their essay, which not only makes the essay difficult to read but detracts form the information provided. If you use any resource to help you write an essay then I recommend that you list the resources that you use (including links to any webpages) in a bibliography at the end of the essay. It is also important that you use these resources to write an account in your own words, your teacher is interested in what you have to say and how much you understand the topic not someone else. Finally the candidate gives an acceptable conclusion, they have clearly attempted to bring the essay to a close by mentioning key facts from within the essay. Though this could be improved by writing an personal reaction and summarising all of the key points.

Response to question

The candidate has attempted to write a suitable introduction but they have given too much detail. A good introduction should be brief and to the point. It is there to introduce your topic, save the finer details for the bulk of the essay. You should also make sure that the premise of your essay is clear, this can be achieved by stating exactly what you plan to discuss. Remember this is your chance to engage the reader, which can be done by stating a interesting fact or quote related to your topic. That said, the candidate gives a detailed response to the set topic.

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