![]() ![]() If this seems like an overly technical definition for a term that you hear used all the time in weather forecasts, then that’s because it is. Partly cloudy is a relatively difficult type of weather to define, but it exists somewhere between sunny and cloudy.Īccording to NOAA (National Oceanic and Atmospheric Administration), the term “ partly cloudy” is used when the sky has between 3/8 and 5/8 cloud cover. ![]() Compare that to the fewer than 70 cloudy days that Phoenix, Arizona gets each year, and it’s clear that not all cities are built equally as far as clouds are concerned. That means that the residents of Alaska’s largest city only get sunshine about 40% of the time. Some places also get cloudy conditions on a daily basis as a result of their local topography or weather systems.įor example, Anchorage, Alaska receives over 230 cloudy days each year. But when we’re talking about cloudy weather, we’re generally referring to conditions where at least half-but not all-of the sky is covered in clouds.Ĭloudy conditions can happen for a wide variety of reasons, though they’re typically the result of local or regional low pressure. There are dozens of different types of clouds out there. ![]() Depending on where you live, sunny conditions might be quite fickle, especially if local weather patterns generally cause clouds to build up in the afternoon and evening. We generally experience sunny weather whenever there’s a high pressure system, or an anticyclone, overhead. Technically, if these conditions happen at night, we would call them “clear” rather than “sunny” due to, well, the lack of sun. Sunny weather happens whenever there are few, if any clouds overhead. When the sun’s shining, we can enjoy all sorts of superb outdoor activities, like hiking and climbing, or we can simply sit out in nature and enjoy the world around us. When it comes to weather, there’s nothing better than a nice, calm sunny day. Here’s a quick look at 9 different weather that any aspiring storm chaser ought to be familiar with. Findings of this study contribute to the effective traffic control and management to enhance road safety under hazy weather conditions.Of all of the different kinds of weather that we might experience, there are 9 that many people will experience at least once in their lives. The plausible causal relationships among the weather conditions, driving performance changes and collision risk are analyzed and discussed. Moreover, the variations in speeds under hazy weather conditions are higher than those under clear weather conditions when the speed is high or medium. However, no significant evidence is found for the relationship between weather conditions and distance or time headways when the vehicular speed is low or medium. Both the distance and time headways under hazy weather conditions are lower than those under clear weather conditions when the vehicular speed is high. In addition, the interaction effects of vehicular speed on the relationship between weather conditions and some driving performance metrics are significant. For car-following behavior, under hazy weather conditions, the average reaction time is higher and the sensitivity to the change in car-following spacing is lower. The increase in the low collision risk is more noticeable than that of the high collision risk. The TET and TIT with a critical time-to-collision threshold value of 5 s under hazy weather conditions are 35.9% and 43.0% higher, respectively, than those under clear weather conditions. Results indicate that hazy weather conditions have significant impacts on traffic safety in terms of increased collision risk and impaired car-following performance. The collision risks under different weather conditions as indicated by two surrogate measures – time exposed time-to-collision (TET) and time integrated time-to-collision (TIT) – are compared. A high-fidelity driving simulator is applied to collect vehicle trajectory data concerning a number of driving performance metrics under both clear and hazy weather conditions. This paper examines the impacts of reduced visibility under hazy weather conditions on collision risk and car-following behavior to enhance the understanding of relationships among weather conditions, driving performance and road safety. ![]()
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