Mesoscale meteorology in the context of "Microscale meteorology"

In meteorology, prevailing wind in a region of the Earth's surface is a surface wind that blows predominantly from a particular direction. The dominant winds are the trends in direction of wind with the highest speed over a particular point on the Earth's surface at any given time. A region's prevailing and dominant winds are the result of global patterns of movement in the Earth's atmosphere. In general, winds are predominantly easterly at low latitudes globally. In the mid-latitudes, westerly winds are dominant, and their strength is largely determined by the polar cyclone. In areas where winds tend to be light, the sea breeze-land breeze cycle (powered by differential solar heating and night cooling of sea and land) is the most important cause of the prevailing wind. In areas which have variable terrain, mountain and valley breezes dominate the wind pattern. Highly elevated surfaces can induce a thermal low, which then augments the environmental wind flow. Wind direction at any given time is influenced by synoptic-scale and mesoscale weather like pressure systems and fronts. Local wind direction can also be influenced by microscale features like buildings.

Wind roses are tools used to display the history of wind direction and intensity. Knowledge of the prevailing wind allows the development of prevention strategies for wind erosion of agricultural land, such as across the Great Plains. Sand dunes can orient themselves perpendicular to the prevailing wind direction in coastal and desert locations. Insects drift along with the prevailing wind, but the flight of birds is less dependent on it. Prevailing winds in mountain locations can lead to significant rainfall gradients, ranging from wet across windward-facing slopes to desert-like conditions along their lee slopes.

In meteorology, air currents are concentrated areas of winds. They are mainly due to differences in atmospheric pressure or temperature. They are divided into horizontal and vertical currents; both are present at mesoscale while horizontal ones dominate at synoptic scale. Air currents are not only found in the troposphere, but extend to the stratosphere and mesosphere.

Wind shear (/ʃɪər/; also written windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude.

Wind shear is a microscale meteorological phenomenon occurring over a very small distance, but it can be associated with mesoscale or synoptic scale weather features such as squall lines and cold fronts. It is commonly observed near microbursts and downbursts caused by thunderstorms, fronts, areas of locally higher low-level winds referred to as low-level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. Wind shear has significant effects on the control of an aircraft, and it has been the only or a contributing cause of many aircraft accidents.

A high-pressure air system, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interplays between the relatively larger-scale dynamics of an entire planet's atmospheric circulation.

The strongest high-pressure areas result from masses of cold air which spread out from polar regions into cool neighboring regions. These highs weaken once they extend out over warmer bodies of water.

An outflow boundary, also known as a gust front, is a storm-scale or mesoscale boundary separating thunderstorm-cooled air (outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature and a related pressure jump. Outflow boundaries can persist for 24 hours or more after the thunderstorms that generated them dissipate, and can travel hundreds of kilometers from their area of origin. New thunderstorms often develop along outflow boundaries, especially near the point of intersection with another boundary (cold front, dry line, another outflow boundary, etc.). Outflow boundaries can be seen either as fine lines on weather radar imagery or else as arcs of low clouds on weather satellite imagery. From the ground, outflow boundaries can be co-located with the appearance of roll clouds and shelf clouds.

Outflow boundaries create low-level wind shear which can be hazardous during aircraft takeoffs and landings. If a thunderstorm runs into an outflow boundary, the low-level wind shear from the boundary can cause thunderstorms to exhibit rotation at the base of the storm, at times causing tornadic activity. Strong versions of these features known as downbursts can be generated in environments of vertical wind shear and mid-level dry air. Microbursts have a diameter of influence less than 4 kilometres (2.5 mi), while macrobursts occur over a diameter greater than 4 kilometres (2.5 mi). Wet microbursts occur in atmospheres where the low levels are saturated, while dry microbursts occur in drier atmospheres from high-based thunderstorms. When an outflow boundary moves into a more stable low level environment, such as into a region of cooler air or over regions of cooler water temperatures out at sea, it can lead to the development of an undular bore.