bulk Richardson number

1. An approximation to the gradient Richardson number formed by approximating local gradients by finite difference across layers.
   The bulk Richardson number R_B is

   

   where g is gravitational acceleration, T_v is absolute virtual temperature, Δθ_v is the virtual potential temperature difference across a layer of thickness Δz, and ΔU and ΔV are the changes in horizontal wind components across that same layer. In the limit of layer thickness becoming small, the bulk Richardson number approaches the gradient Richardson number, for which a critical Richardson number is roughly Ri_c = 0.25. Gradient Richardson numbers less than this critical value are dynamically unstable and likely to become or remain turbulent. Unfortunately, a critical value is not well defined for the bulk Richardson number, leading to uncertainty in turbulence likelihood for values near the critical value.
   See Richardson number.
   
2. In the context of convective storm forecasting, a nondimensional ratio of the convective available potential energy (CAPE) to a measure of the vertical wind shear, used to characterize convective-storm types for various environments.
   The vertical wind shear is one-half the square of the difference between the 6-km density- weighted mean wind speed and a 500-m mean surface layer wind speed. Generally, values of the bulk Richardson number less than 45 support supercell convection, while values greater than 45 support multicell or ordinary cell convection.
   Weisman, M. L., and J. B. Klemp 1986. Characteristics of isolated convective storms. Mesoscale Meteorology and Forecasting. P. Ray, Ed., Amer. Meteor. Soc., ch. 15, . 504–520.
   

número de Richardson global

1. Es una aproximación al número de Richardson de gradiente que se forma al aproximar los gradientes locales mediante la diferencia finita entre capas.
   El número de Richardson global RB es

   

   donde g es la aceleración gravitacional, Tv es la temperatura virtual absoluta, Δθv es la diferencia de temperatura potencial virtual entre una capa de espesor Δz, y ΔU y ΔV son los cambios en los componentes del viento horizontal a través de esa misma capa. En el límite de que el espesor de la capa se vuelve pequeño, el número de Richardson global se aproxima al número de Richardson de gradiente, para el que un número de Richardson crítico es aproximadamente Ric = 0.25. Los números de Richardson de gradiente menores que este valor crítico son dinámicamente inestables y es probable que se vuelvan o permanezcan turbulentos. Desafortunadamente, un valor crítico no está bien definido para el número de Richardson global, lo que lleva a incertidumbre en la probabilidad de turbulencia para valores cercanos al valor crítico. Consulte número de Richardson.
   
2. En el contexto de la predicción de tormentas convectivas, una tasa no dimensional de la energía potencial convectiva disponible (CAPE, por sus siglas en inglés) a una medida de la cizalladura vertical del viento, utilizada para caracterizar los tipos de tormentas convectivas para diversos entornos.
   La cizalladura vertical del viento es la mitad del cuadrado de la diferencia entre la velocidad media del viento ponderada por densidad de 6 km y una velocidad del viento promedio de la capa superficial de 500 m. Generalmente, los valores del número de Richardson global menores que 45 admiten la convección de supercélulas, mientras que los valores mayores que 45 admiten la convección de células multicelulares u ordinarias.

Term edited 24 August 2023.

The dimensionless ratio of buoyant suppression of turbulence to shear generation of turbulence.

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Lines or surfaces associated with a partial differential equation, or with a set of such equations, which are at all points tangent to characteristic directions, determined by certain specified linear combinations of the equations.

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An imaginary bundle of propagating electromagnetic or acoustic energy, the lateral dimensions of which are negligible.

A series of operational polar-orbiting meteorological satellites launched by the former Soviet Union since 1969.