IJBET 2017 Volume 6 Issue 4

International Journal of BioEngineering and Technology (IJBET) ISSN: 0976 - 2965

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Title:
Impact of cloudiness on longwave radiation exchange at exterior greenhouse surfaces

Authors & Affiliation:
Erick Kiplangat Ronoh
Agricultural and Biosystems Engineering Department, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya 

ABSTRACT:
Cloudiness influences the weather on earth and especially the longwave radiation received by exterior surfaces of buildings such as greenhouses. Precise estimation of cloudiness is therefore vitally important for numerous applications in agriculture requiring surface radiation and energy balance. This study aims at estimating cloudiness factors using two approaches (octas and weather maps) and testing their usage in longwave radiation simulation at an experimental greenhouse surface. With this information, the problem of missing cloudiness data at any given time and in any location can be solved. From this study, the results indicate that better model predictions of longwave radiation were obtained by simulation with weather maps than with octas. Hence, map-based simulation data are accurate and precise enough for this kind of energy application. Despite the slight variations, the usage of cloudiness factors showed insignificant differences in terms of radiation simulation. Overall, the generated cloudiness information could be used in various agricultural modelling applications.
Keywords: cloudiness; longwave radiation exchange; exterior surface; greenhouse; agriculture; energy