Aerosol-Cloud Interactions: A Piece of the Climate Puzzle - Literature review Example

 AEROSOL-CLOUD INTERACTIONS – A PIECE OF THE CLIMATE PUZZLE The climate as always is and always will be, will remain the most important part of the change in the weather both now and in the near future. There are a number of definitions to the term aerosols, but the most relevant one in this case is that they are air bone solid or liquid substances with a typical size and they stay in the atmosphere for at least several hours. The interactions that always occur between the aerosols and the clouds both microphysical and dynamical interrelations have been connected to a few of the biggest uncertainties in protuberance of future climate. There have been a number of potential effects about the aerosols that have been implied though there should be much more investigation and study in order for the size of these effects in a worldwide view. Therefore, for a much more improved model outcrop of future climate, there is much importance in the quantitative comprehension of these effects. There are findings that have been put into writing as well as pictures in regard to the aerosol and cloud properties during the previous years. Nonetheless, these types of seen connection are not essentially as a result of microphysical end products. They may relatively be as a result of retrieval errors, cloud flagging errors, seasonal factors, spatial climatological factors, humidity conditions or even synoptic effects. This report herein shows a discussion of the contribution of spatial climatological factors and synoptic effects to aerosol-cloud associations. Therefore, this paper is going to handle the needed aspects that deal with the aerosol and cloud interactions, a piece of the climate puzzle. In addition, that will entail all the necessary details required. Aerosols in as much as is known always have an effect in the cloud formation in general. There are, therefore, specific aerosols that can be found in the clouds, whether they are organic or inorganic. The specific organic or inorganic aerosol found in the clouds is a sea salt, which is the most common CCN over the ocean. It is mostly how they aerosols affect or get involved in the cloud formation. To add to that, there is the question of what happens when these major oceanic clouds move over land and whether the aerosol interactions change (Bowler 76). The answer that comes to that question is that, once droplets of clouds have been formed, aerosols or CCN are separated by water of ice and would not be directly interacting with anything else. As a result, when cloud droplets or raindrops evaporate, aerosols are free and can be able to become CCN again. This process is known as reactivation. Moreover, it is what usually occurs in the process. These aerosols can be either man made or natural and differ in the ration that they exist in. The ratio in which these aerosols occur over land is over 70%, which represent the most of them that are anthropogenic. Whereas over the ocean, natural aerosols (dust and sea salt) take over. That herein shows how the aerosols differ in the ratio over land as well as over sea or ocean (Gelencser 67). Aerosols play a role in the weather that is always experienced during the winter up North. It is because the aerosols are necessary for the cloud formation everywhere, though weather pattern changes are mainly due to the dynamic (airflows), not aerosol. There are areas in the world that have many more cloud cover than the others, and this is possibly due to pollution or other factors. Bringing out the question of how long it takes the clouds to dissipate. The dissipation of clouds is always through precipitation or evaporation (Holloway 109). In addition, as discussed, precipitation dissipates cloud much faster than evaporation. The typical cloud lifetime is always one to several hours, though there are clouds that appear to last much longer, for example, those in a hurricane, tough they are mostly regenerated instead of lasting beyond a few hours. What kind of aerosols make clouds most reflective? The fact is that, the sizes of water-soluble aerosols affect the reflective property of clouds. As explained earlier, high number, density of aerosols may cause more cloud droplets of smaller sizes, which, as a result leads to longer lifetime and enhancement of reflectivity (Metz 56). Does having a large enough CCN prevent precipitation, for example, does the Saharan dust prevent or induce precipitation? There are research studies that have been carried out, and they suggest that the Saharan and Asian dust and biological aerosols, as an important source of Ice Nuclei, may enhance precipitation in some regions. On the other hand, Saharan dust also comes in with dry air, which as always is known, is detrimental to precipitation, and as a result, the net effect of Saharan dust is to suppress precipitation. Rain comes from clouds, and there are questions as to whether clean cloud or polluted cloud will result in raining. The answer is; clean air has relatively minimum cloud condensation nuclei per unit volume. Thus, it means that only about 100 cloud droplets are formed in every cubic centimeter of air. The polluted air, in contrast, has more than 1000 cloud condensation nuclei per cubic centimeter – mainly in the form of increased smoke and aerosol particles. Since the overall amount of water in polluted and non-polluted clouds at a certain point is the same, the liquid in dirty clouds spreads over a huge number of smaller droplets (Bowler 82). In other words, there are many minor droplets in polluted clouds that cannot easily grow into major drops of precipitation size on cloud formation. Pollution hinders rainfall to certain degrees. There are different size range of aerosol to form clouds, as well as the difference between cloud and haze. A typical CCN is in the order of 0.1 micrometer in diameter, in comparison to 2mm for a raindrop, and 0.02mm for cloud droplet. Haze is majorly an atmospheric occurrence where dust, smoke and other dry particles (aerosols) obscure the clarity of the sky (Gelencser 85). The sources those are responsible for haze particles include farming (plowing of dry land), traffic, industry, and wildfires. A cloud is a visible mass of water liquid droplets or ice crystals form on aerosol (CCN). Clouds can also be affected by the different kinds of currents that occur globally. Sea surface temperature has great impacts on the atmosphere above, while the distribution of sea surface temperature highly depends on the surface wind-driven currents. For example, in California and Namibia, the equator-ward boundary currents and the strong wind-driven upwelling lead to cool and stable climates in the coastal regions. These regions are always cloudy and foggy, and strong convective systems rarely occur (Holloway 96). An ice cloud is a different cloud from the normal cloud, and that is in this way; in ice cloud, cloud particles are ice crystals, as opposed to water droplets in warm low clouds. Both these two clouds are formed or occur in a regular basis, in many places the world over. In another area of the research, it was observed that there are many tools that can be used in the observation of cloud-aerosol-drizzle interaction studies. In as much as there are a number of tools, the best was found out to be the Radar and Lidar (“light radar”) mounted on aircraft are widely deployed to measure droplets types and sizes (Metz 111). As part of the research studies in the question and answer, there was also part of cloud seeding and geoengineering. In addition, there was a question whether there are ways that may be used in relation to clouds that could cause cooling. The result that was got was that this is an issue of geoengineering, which was found to be controversial and under debate, as well. What will occur on a larger scale if the humans continue to try to change the climate? Because humans do not fully understand the climate system, they cannot precisely predict the outcome of what happens to nature. Even when the intentions might be good and noble, there might be unintended consequences to face. Quite too many indices have been seen in history. There are many activities that humans have carried out in an attempt to add aerosols to the atmosphere. Humans cannot control volcanoes, as they are a thing of nature. Natural eruptions have in the past affected climate on a temporary basis because volcanic ashes eventually fall on the ground. Again, massive volcanic eruptions have been hypothesized as a cause of mass extinction in the Earth history. The best option is to stay away from volcanoes at all costs. Dust as well is an aerosol and, therefore; there would be no difference in releasing aerosols or releasing dust in the atmosphere (Bowler 121). Cloud seeding on hurricanes has been tried to no definite outcomes so there is no proof as to whether the experiment would strengthen or disintegrate hurricanes. In other researches was if manipulating aerosol concentration be used in ending a drought. There have been many attempts with no result definitive enough to justify the cause. Drought is mostly caused by change in airflow patterns that deviate water vapor transport to somewhere else. Therefore, without water vapor supplies no matter what you do, you cannot make it rain (Holloway 113). In cloud seeding, this has to be a multi-national initiative and not only for the US to have a global scale effect of reducing or slowing down the global warming that we are experiencing. However, before any large scale experiments, the pros and cons of every possible geoengineering concept need to be carefully examined. The cloud seeding theory and practical part of it have not been yet proven effective. In respect to global warming again, ideas like the aerosol spray vessel attempting to alter global warming cannot be confirmed. The result has been that this geoengineering has been debated, and more is to be known before the project has to be deemed feasible and effective (Metz 122). Does the aspect of cloud seeding add harmful chemicals into the atmosphere and what are the disadvantages of cloud seeding? The types of aerosols used for cloud seeding are usually non-toxic. However, the exact advantages and disadvantages of cloud seeding, whether it is effective or economic, are still under debate. In addition, in trying to control aerosols and clouds, will that result in reflection coming back towards the surface and causing the surface to warm up even more. The aerosol effects were found to be focusing on low clouds, since most of the pollutions occur in the lower troposphere. The back radiation of a cloud is controlled by the cloud temperature, which is related to its altitude. For low clouds, increasing reflectivity due to decreasing sizes of cloud droplets may decrease the downward shortwave radiation, while increasing lifetime of clouds may trap even more radiation from the surface. This is just why aerosols remain the greatest uncertainties in the climate models: these effects and processes are too complicate for us to determine their combined effect. There has not been any man made cloud attempt that would be more beneficial to possibly helping our climate. How can you manufacture large CCN particles without tons of small ones generated? What are major natural aerosols? Natural aerosol is the most common condensation nuclei in pristine environments. Any attempts of deliberately producing CCNs may include aerosols of all different sizes. What matters is the size-distribution that matters (Gelencser 133). The aerosols also have disadvantages such as pollution, which is not so good to the atmosphere itself. The most source of pollution that emits the most aerosols depends on the region. In developed countries, the most of aerosols comes from industrial pollution, and in agriculture-dominated areas, the aerosols are from biomass burning. How have clouds changed throughout Earth’s history? Has the increase of pollution and aerosols increased the number of clouds? Global cloud observations only started when we had satellite the 1970’s. The record is too short to detect any long-term trend. In short-term, number of clouds changes is because of natural processes. What other effects on clouds result from pollution? How does that affect ecosystems? - Acid rain, caused by emissions of sulfur dioxide and nitrogen oxide. Acid rain has been shown to have bad effects on forests, freshwaters and soils, killing flying and aquatic life forms as well as causing damage to structures and having effects on human health (Metz 143). The long-term effects of increased aerosols due to human actions have been done. It is a current research topic, and cannot be concluded which effect of aerosol-cloud-interactions on radioactive forcing dominates. A hypothesis is that anthropogenic CCNs may increase cloud lifetime, diminish precipitation, and increase reflectivity, thus less solar radiation will reach Earth surface. There are plenty of CCNs usually in the air, so when there are no clouds that are because of other meteorological conditions, for example, dry air. Another thing is that aerosols do not strengthen storms and the strength of the storm come from or is determined by other meteorological conditions. The solutions that can be used in solving some issues that are related to the cloud-aerosol interactions and climate change can be this. There has to be more observation and improvement in the understanding of the science of cloud formation. Eventually, improved understanding will lead to improvement of the models that are used in forecasting cloud behavior, especially the climate change feedback. Only after the understanding well the physical process of the cloud can there be effective solution seeking to issues that are related to cloud-aerosol-climate interactions. The other challenging question is that can cloud formation be affected by global warming since clouds require cooling to form. The cooling of cloud-formation processes can be easily satisfied by lifting of an air parcel, either mechanic or thermal. Global warming would increase the amount of vapor in the air. How this may affect clouds is a research topic that is without a definite answer. Global dimming effects have been found to reduce the impact of global warming. Aerosols and its associating effects remain one of the greatest uncertainties in climate research. The combined effect of dimming and warming is a current research topic. If global dimming balanced or slow down the warming, it would be beneficial. But, if this leads to the belief that pollution is good, then it’s bad (Bowler 153). In conclusion, this paper has handled the required issues that entail the interaction between the aerosols and the clouds. In addition, it is to find a solution to the climate puzzle that is encountered on a daily basis globally. Work cited: Acid Rain Abstracts Annual. New York: Bowker A & I Pub, 2008. Print. Gelencsér, András. Carbonaceous Aerosol. Dordrecht, the Netherlands: Springer, 2004. Internet resource. Holloway, Ann M, and Richard P. Wayne. Atmospheric Chemistry. Cambridge: RSC Pub, 2010. Print. Metz, Bert. Ipcc/teap Special Report on Safeguarding the Ozone Layer and the Global Climate System: Issues Related to Hydrofluorocarbons and Perfluorocarbons. Cambridge: Cambridge Univ. Press, 2005. Print. Read More