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cold wave. Also cold spell and cold snap. A period of weather characterized by excessively low temperatures, which may or may not also be accompanied by changes in humidity. Very cold weather is often only referred to as a cold wave if the temperature, or the rate at which the temperature decreases within a given time period, is abnormal ...
Since stronger high-pressure systems contain cooler or drier air, the air mass is more dense and flows towards areas that are warm or moist, which are in the vicinity of low pressure areas in advance of their associated cold fronts. The stronger the pressure difference, or pressure gradient, between a high-pressure system and a low-pressure ...
that is, the difference in flow velocity between points separated by a vector r (since the turbulence is assumed isotropic, the flow velocity increment depends only on the modulus of r). Flow velocity increments are useful because they emphasize the effects of scales of the order of the separation r when statistics are computed.
The low air pressure causes air flowing towards the vortex to expand and cool. If the air is sufficiently moist and cools to the dew point, a funnel cloud is produced. The air pressure around the outer edge of the funnel cloud generally corresponds to the air pressure of the cloud base of the parent cloud. [4]
Airflow, or air flow, is the movement of air. Air behaves in a fluid manner, meaning particles naturally flow from areas of higher pressure to those where the pressure is lower. Atmospheric air pressure is directly related to altitude , temperature , and composition.
Turbulent flow is defined as the flow in which the system's inertial forces are dominant over the viscous forces. This phenomenon is described by Reynolds number, a unit-less number used to determine when turbulent flow will occur. Conceptually, the Reynolds number is the ratio between inertial forces and viscous forces.
A spell of freezing weather will descend on North Texas by the end of the week, and the Electric Reliability Council of Texas (ERCOT) says it will have enough electricity for the winter.
Hot areas are shown in red, cold areas are shown in blue. A hot, less-dense material at the bottom moves upwards, and likewise, cold material from the top moves downwards. Convection (or convective heat transfer) is the transfer of heat from one place to another due to the movement of fluid.