التباين في تكرار سكون الهواء خلال الرصدات الساعية في العراق

الملخص EN

The phenomenon of air calm occurs when the wind speed decreasing to (0-0.

2) m/s.

The air is calm and stable and is unable to move things such as leaves and flags, as it is a common climatic phenomenon for Iraq's climate, and this phenomenon occurs at all hours of the day and in all months for the year, but they vary according to the hours of the day, their frequency varies between night and daytime and between morning to evening, Their frequency is affected by local conditions, surface roughness and the pressure systems, Calm frequency increases in times that are free from cyclones and frontal deprations.

The study aims to calculate the frequency of the phenomenon of air calm in Iraq on all days of the year for a period of time up to (11) years for the years (2007-2017), By relying on hourly wind speed data during (24) hours a day for seven meteorological stations in Iraq, and extracting the percentages of their frequency every hour of the monitoring times in the meteorological stations and in all months of the year.

The study showed a variation in the frequency of this phenomenon during the hours of the day, as it recorded the most frequent during the observation (00 : 00) GMT and the lowest in the observation (12 : 00) GMT, and it was also found that they differ from one month to another and between one region and another.