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e. A fire whirl, fire devil or fire tornado is a whirlwind induced by a fire and often (at least partially) composed of flame or ash. These start with a whirl of wind, often made visible by smoke, and may occur when intense rising heat and turbulent wind conditions combine to form whirling eddies of air. These eddies can contract to a tornado ...
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis (cell death). [1] Symptoms can overlap across causal agents, however ...
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, [ 1 ] although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the ...
Usually, within the lower atmosphere (the troposphere) the air near the surface of the Earth is warmer than the air above it, largely because the atmosphere is heated from below as solar radiation warms the Earth's surface, which in turn then warms the layer of the atmosphere directly above it, e.g., by thermals (convective heat transfer). [3]
Cumulonimbus (from Latin cumulus 'swell' and nimbus 'cloud') is a dense, towering, vertical cloud, [1] typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. Above the lower portions of the cumulonimbus the water vapor becomes ice crystals, such as snow and graupel ...
Liquid forms of precipitation include rain and drizzle and dew. Rain or drizzle which freezes on contact with a surface within a subfreezing air mass gains the preceding adjective "freezing", becoming the known freezing rain or freezing drizzle. Slush is a mixture of both liquid and solid precipitation. Frozen forms of precipitation include ...
Diabrotica undecimpunctata, the spotted cucumber beetle or southern corn rootworm, is a species of cucumber beetle that is native to North America. The species can be a major agricultural pest insect in North America. Spotted cucumber beetles cause damage to crops in the larval and adult stages of their life cycle.
In horticulture, mildews are species of fungus in the order Erysiphales, or fungus-like organisms in the family Peronosporaceae. It is also used more generally to mean mold growth. In Old English, mildew meant honeydew (a substance secreted by aphids on leaves, formerly thought to distill from the air like dew), and later came to mean mold or ...