Clouds from Space: Noctilucent AKA Polar Mesospheric Clouds

Astronomy, Meteorology
[caption id="attachment_24116" align="alignright" width="480"] An International Space Station image of noctilucent clouds. Image by ISS/NASA[/caption] A cloud is a visible collection of condensed water vapor or ice crystals located within the atmosphere. Clouds form only when there is sufficient humidity to form droplets or crystals upon a suitable quantity of microscopic particles (called an aerosol). Particle types include sand, pollen, spores, smoke, exhaust pollutants, and sea salt. But the formation of so-called “night shining” or ‘noctilucent’ clouds (NLCs) requires something special. Noctilucent clouds are sometimes (especially in scientific circles) called polar mesospheric clouds (PMCs) – their appearance is striking. Their altitude is remarkable. They reside an amazing 50 miles above Earth’s surface. By comparison, cumulonimbus (storm) clouds reach elevations of only approximately 15 miles, and cumulus (fair weather) clouds are…
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Our Planet and Atmosphere: Ozone – the “Other” Oxygen

Health, Technology
[caption id="attachment_20184" align="alignright" width="440"] The Blue Ridge Mountains of Virginia[/caption] Oxygen atoms are very reactive chemically. We call them electrophilic or "electron loving" because the oxygen atom seeks to bind to other electron-rich sources, especially itself. Thus oxygen is present in our atmosphere primarily as the molecular O₂. Another Form A small percentage of atmospheric oxygen exists in another form, ozone, O₃. This less stable form of oxygen is produced by ultraviolet light or high voltage electrical discharge. It's garlicky odor may be discerned after a heavy thunderstorm. Geometry The O₂ molecule consists of only two atoms, and two points make a line, right? So what shape is the O₃ molecule? Unlike its more abundant companion, ozone is non-linear. As a result, it carries partial charges on its constituent atoms.…
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