The wind patterns at F-region altitudes during periods of geomagnetically quiet conditions can be represented by the pressure gradient associated with solar radiation and geostrophic force balance induced by the Coriolis and centrifugal forces. While ions are minor species in the upper atmosphere or partially ionized plasma, the presence of ionized gas substantially affects the thermospheric wind. Thermospheric wind dynamics at high latitudes are significantly affected by ionospheric plasma motions through particle collisions between ions and neutrals, which is known as ion drag. This is the first study to report a dawn-dusk asymmetry of the thermospheric wind acceleration feature and signatures of the eastward wind acceleration at dawn by ion drag. Deviations from the quiet-time wind presented similar patterns in the direction with the ionospheric plasma convection but were larger in magnitude at dusk than at dawn. With an increase in the geomagnetic activity level, the thermospheric wind turned over from eastward to westward at dusk and increased the equatorward magnitude from midnight to dawn. The quiet-time wind pattern can be expected to be represented by a pressure gradient associated with the solar radiation and a geostrophic force balance. The measurements were sorted by a SuperMAG (SME) index, and a quiet-time wind pattern was defined as an hourly mean under SME ≤ 40 nT. We performed a statistical analysis of the thermospheric wind measurements with a Fabry–Perot interferometer (FPI 630 nm wavelength) in Tromsø, Norway, in the winter months for 9 years. Each pair of Cocoons comes with an informative Use & Care Guide and is protected by a Lifetime Warranty.Ion drag associated with the ionospheric plasma convection plays an important role in the high-latitude thermospheric dynamics, yet changes in the thermospheric wind with geomagnetic activity are not fully understood. The buoyancy of the case is such that if you were to drop it in the water, with your Cocoons fitover sunglasses and even your car keys in it, it will remain afloat!Īlso included, the ultra-soft DuraCloth is designed to effectively remove moisture, finger prints, facial oils and other contaminants that can cloud the lens surface and reduce visual acuity. The case is sealed with a corrosion-proof, premium quality coil zipper that will never jam. A top mounted nylon lanyard, featuring a 360° swiveling nylon hook-clip provides an additional attachment method. The case features a belt clip on the reverse side, allowing for rapid attachment and removal. The thick, yet surprisingly lightweight neoprene scabbard is stain resistant, maintains its form and flexibility in extreme temperatures and is exceptionally robust. Manufactured from the highest quality neoprene, the Cocoons case is virtually indestructible. INCLUDED ACCESSORIES Our Famous Case & Duracloth Included!Įvery pair of Cocoons includes our world famous Cocoons case. They are a life saver.” (5 / 5) Michelle V., Hilo, Hawaii I recommend the Twilight Cocoons for anyone who can’t see clearly at night. “Nothing like the as-seen-on-tv rubbish! These actually make driving at night possible. Eye-strain and fatigue is greatly reduced as objects become clearer and more easily visible. Your eyes will remain relaxed and focused. The Twilight lens system is effective at night or in foggy/rainy conditions. The scientifically engineered tint also enhances contrast to improve depth perception. The Cocoons Twilight collection reduces oncoming glare with an anti-reflective lens system that also blocks high energy visible blue light, such as that produced by modern LED headlights. As the eye ages, it becomes more light sensitive, making oncoming headlight glare more problematic. Seeing clearly in darkened conditions becomes especially challenging. Drivers over 60 might only receive half of the light transmission they did when they were 20, which can potentially make night driving difficult, even dangerous. The pupil becomes less responsive and ultimately lets in less light. Night driving can become problematic for many people as they age.
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