3/10/2024 0 Comments Balanced flow meter![]() This speed is always a positive quantity, since any parcel moves along its own trajectory and, for increasing times (d t>0), the trodden length increases as well (d s>0). The velocity vector ( V) is oriented like s and has intensity ( speed) V = d s/d t. This frame is termed natural or intrinsic because the axes continuously adjust to the moving parcel, and so they are the most closely connected to its fate. The frame of reference ( s, n) is shown by the red arrows in the figure. The radius of curvature approaches an infinite length at the points where the trajectory becomes straight and the positive orientation of n is not determined in this particular case (discussed in geostrophic flows). The distance between the parcel position and the centre of curvature is the radius of curvature R at that position. The centre of curvature is found on the 'inner side' of the bend, and can shift across either side of the trajectory according to the shape of it. The trajectory at a position s has one tangent unit vector s that invariably points in the direction of growing s 's, as well as one unit vector n, perpendicular to s, that points towards the local centre of curvature O. When we consider the motion determined by the forces selected next, we will have clues of which type of trajectory fits the particular balance of forces. In this section we assume to know it from the start for convenience of representation. In reality, however, the trajectory is the outcome of the balance of forces upon the particle. The position of the packet is defined by the distance on the trajectory s= s( t) which it has travelled by time t. The momentum equations are written primarily for the generic trajectory of a packet of flow travelling on a horizontal plane and taken at a certain elapsed time called t. The momentum equations in natural coordinates Trajectories In particular, the balanced-flow speeds can be used as estimates of the wind speed for particular arrangements of the atmospheric pressure on Earth's surface. The idealisation consists in considering the behaviour of one isolated parcel of air having constant density, its motion on a horizontal plane subject to selected forces acting on it and, finally, steady-state conditions.īalanced flow is often an accurate approximation of the actual flow, and is useful in improving the qualitative understanding and interpretation of atmospheric motion. In atmospheric science, balanced flow is an idealisation of atmospheric motion. JSTOR ( September 2018) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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