{{Short description|Weather phenomenon}} [[File:Hand of the Gods.jpg|thumb|A cloud appears to set be place by a human hand{{Clarification needed|date=July 2022}}|alt=A cloud appears to be set in place by a human hand]]
'''Deformation''' is the rate of change of shape of fluid bodies. Meteorologically, this quantity is very important in the formation of atmospheric fronts, in the explanation of cloud shapes, and in the diffusion of materials and properties.<ref name="Djurić, D 1994">Djurić, D: "Weather Analysis". Prentice Hall, 1994. {{ISBN|0-13-501149-3}}.</ref>
==Equations== The deformation of horizontal wind is defined as <math> \operatorname{def} \mathbf{V} = \sqrt{A^2 + B^2}</math>, where <math>\ A = \frac{\partial v}{\partial x} + \frac{\partial u}{\partial y}</math> and <math>\ B = \frac{\partial u}{\partial x} - \frac{\partial v}{\partial y}</math>, representing the derivatives of wind component. Because these derivatives vary greatly with the rotation of the coordinate system, so do <math>\ A</math> and <math>\ B</math>.<ref name="Djurić, D 1994" />
==Stretching direction== The deformation elements <math>\ A</math> and <math>\ B</math> (above) can be used to find the ''direction of the dilatation axis'', the line along which the material elements stretch (also known as the ''stretching direction''). Several flow patterns are characteristic of large deformation: confluence, diffluence, and shear flow. '''{{visible anchor|Confluence}}''', also known as ''stretching'', is the elongating of a fluid body along the flow (streamline convergence). '''{{visible anchor|Diffluence}}''', also known as ''shearing'', is the elongating of a fluid body normal to the flow (streamline divergence).<ref name="Djurić, D 1994" /> [[File:Twilight Cloud Stripes.jpg|thumb|right|Extreme cloud confluence]]
==See also== *Wind shear *Convergence zone *Divergence
==References== {{Reflist}}
{{DEFAULTSORT:Deformation (Meteorology)}} Category:Vector calculus Category:Rates