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بررسی تجربی تأثیر ذرات آبدوست بر تعدیل مه | ||
| فیزیک زمین و فضا | ||
| مقاله 9، دوره 45، شماره 2، مرداد 1398، صفحه 373-382 اصل مقاله (514.68 K) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22059/jesphys.2019.262718.1007027 | ||
| نویسندگان | ||
| امیر باقری مصلحآبادی1؛ عباسعلی علی‌اکبری بیدختی* 2؛ مریم قرایلو3؛ رضا خلیفه4 | ||
| 1دانشجوی کارشناسی ارشد، گروه فیزیک فضا، مؤسسه ژئوفیزیک، دانشگاه تهران، تهران، ایران | ||
| 2استاد، گروه فیزیک فضا، مؤسسه ژئوفیزیک، دانشگاه تهران، تهران، ایران | ||
| 3استادیار، گروه فیزیک فضا، مؤسسه ژئوفیزیک، دانشگاه تهران، تهران، ایران | ||
| 4دانشجوی کارشناسی ارشد، دانشکده ریاضی، آمار و علوم کامپیوتر، دانشگاه تهران، تهران، ایران | ||
| چکیده | ||
| تشکیل مه باعث کم شدن دید افقی میشود و دید افقی پایین میتواند باعث بروز مشکلاتی عمدتاً در فرودگاهها و جاده‌ها شود. از اینرو با تشکیل مه مصنوعی در آزمایشگاه، تأثیر برخی هواویزها بر روی مه بررسی میشود. ذرات آبدوست میتوانند به‌عنوان هستههای میعان با افزایش شعاع مؤثر و کاهش غلظت قطرکها، در تعدیل مه مؤثر باشند. در این مطالعه، آزمایشها بر روی سدیم هیدروکسید، اوره و نمک انجام شده است که با هواویزهای زمینه مقایسه شدهاند. ابتدا عمق نوری مه محاسبه و سپس توزیع اندازه قطرکهای مه تخمین زده میشود. همچنین دیگر پارامترها مانند غلظت قطرکهای مه، محتوای آب مایع و زمان ماندگاری مه، مورد ارزیابی قرار میگیرد. نتایج حاکی از آن است که ذرات آبدوست به‌عنوان هستههای میعان، نقش به‌سزایی را در تعدیل مه ایفا میکنند. بهطوری‌که در حضور این ذرات، غلظت قطرکهای مه در مقایسه با هواویزهای زمینه کاهش یافته است و مه رقیقتر شده است. در حضور ذرات سدیم هیدروکسید غلظت کل قطرکها کاهش زیادی داشته است و مدت‌زمان ماندگاری مه به 31 ثانیه رسیده است که نشان میدهد این ترکیب برای تعدیل مه عملکرد بهتری داشته است. همچنین هنگامی‌که ذرات سدیم هیدروکسید درون محفظه وجود داشتند، به‌طور مشاهداتی قطرکهای بسیار کوچکی که در انتهای فرآیند سه آزمایش دیگر بر روی پرتوی لیزر نوسان میکردند، برای این ذرات وجود نداشتند. | ||
| کلیدواژه‌ها | ||
| ذرات آبدوست؛ بررسی تجربی؛ قطرکها؛ تعدیل مه | ||
| عنوان مقاله [English] | ||
| Experimental study of the effect of hydrophilic particles on fog modification | ||
| نویسندگان [English] | ||
| Amir Bagheri Mosleh-Abadi1؛ Abbas Ali Aliakbari-Bidokhti2؛ Maryam Gharaylou3؛ Reza Khalife4 | ||
| 1M.Sc. Student, Department of Space Physics, Institute of Geophysics, University of Tehran, Tehran, Iran | ||
| 2Professor, Department of Space Physics, Institute of Geophysics, University of Tehran, Tehran, Iran | ||
| 3Assistant Professor, Department of Space Physics, Institute of Geophysics, University of Tehran, Tehran, Iran | ||
| 4M.Sc. Student, Department of Statistics, Faculty of mathematics, statistics & computer Science, University of Tehran, Tehran, Iran | ||
| چکیده [English] | ||
| Fog formation reduces the visibility, and low visibility cause problems mainly in airports and roads. Fog modification or even clearance can reduce such problems. Here, in the laboratory the effects of some aerosols on the modification of artificial fog have been investigated. This research is carried out using the method used in the work of Vajaiac et al. (2014), for hydrophilic particles. These particles, as the fog modification factor, can be effective as condensation nuclei by increasing the effective radius of the droplets and reducing the concentrations of the fog droplets in the fog.. We used a glass chamber with a height of 41cm and diameter of 28 cm in which a red laser and a detector were placed on both sides of the chamber. We dissolved water-soluble compounds in water and by pumping the air into water of the chamber, the bubbles are formed and their breaking led to formation of particles. Then the particles are dispersed inside the chamber, while the pressure inside the chamber was increased with an air pump, and so the temperature was rised. Then suddenly or quasi-adiabaticaly, the pressure is released and hence, the air temperature was dropped creating the fog (cloud). The cloud droplets are mainly formed on these particles. With the formation of droplets, the received laser signal was decreased and after falling all of droplets, the received laser signal reached its primary level. Hence, by measuring the level of drop in the signal and its duration some properties to the cloud structure can be found. In this study, we used sodium hydroxide, urea, and salt particles that was compared with background aerosols affecting the cloud. First, the optical depth of fog was calculated and then size distribution of fog droplets was estimated. Also other parameters like the concentration of the fog droplets, liquid water content and fog lifetime were evaluated. The results show that hydrophilic particles as condensation nuclei played a significant role in fog modification. So, in the presence of these particles, the concentration of fog droplets in comparison with that of the background aerosols, was decreased and the fog was diluted significantly. The maximum of fog lifetime was observed in the presence of background aerosols as 63 s, also these particles have had the lowest effective radius of 7.77µm. In the presence of sodium hydroxide particles, the concentration of total droplets was decreased significantly. In addition, the maximum effective radius was 10.48 µm for these particles. Also, fog lifetime was reduced to 31s which suggests that this component for fog modification has a better performance. The area under the curve’s of the size distribution of droplets for salt and urea were nearly identical, that indicated the concentration of the droplets was close to each other. Parasitic structures might appear in curves of the size distribution of droplets that were smoothed. As the time passed all of the effective radius curves showed decreasing trends due to the fact that, the larger droplets can droped out of the laser beam, so gradually the effective radius should be decreased. In comparison with other compounds, when sodium hydroxide particles were used in the cloud chamber, observationally small droplets that moved up an down in the laser beam weren’t present, hence no oscillations were seen in the laser signal. Considering experimental errors, while neglecting the process of coalescence that might occur in the falling stage of the droplets, when the droplets were passing the laser beam, they appeared at larger sizes, which could lead to an overestimation. The signal noises and non-uniform distribution of condensation nuclei could also be considered as experimental errors. | ||
| کلیدواژه‌ها [English] | ||
| Hydrophilic particles, Experimental study, Droplets, Fog modification | ||
| مراجع | ||
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باقری مصلحآبادی، ا.، علی‌اکبری بیدختی، ع. ع.، قرایلو، م. و خلیفه، ر.، 1397، مطالعه آزمایشگاهی تخمین توزیع اندازه قطرکهای ابر در حضور هواویز دوده، هجدهمین کنفرانس ژئوفیزیک ایران. شوشتری، م. ح.، ناجی، ف. و علی‌اکبری بیدختی، ع. ع.، 1392، بررسی آزمایشگاهی نقش یونها در تشکیل ابر گرم، م. فیزیک زمین و فضا، 39(4)، 123-134. صادقی حسینی، س. ع. و ارکیان، ف.، 1380، بررسی آزمایشگاهی بارورسازی ابرهای گرم، م. فیزیک زمین و فضا، 27(2)، 15-23. فهندژ سعدی، ح.، علی‌اکبری بیدختی، ع. ع.، قرایلو، م. و شوشتری، م. ح. 1394، مطالعه تجربی نقش مواد سطح فعال بر تشکیل ابر گرم در آزمایشگاه، ن. پژوهشهای اقلیم شناسی، (6)، 23 و 24.
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