Term
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Definition
| Horizontal temperature gradient |
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Term
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Definition
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Term
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Definition
Time averaged winds around the entire globe, also known as the general
circulation around the entire atmosphere |
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Term
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Definition
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Term
| Meridional Temperature Gradient |
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Definition
| Global meridional temperature gradient is flat in tropics and polar regions, baroclinic in mid-latitudes (fig 11.3) |
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Term
| Thermal Wind Relationship |
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Definition
| Relationship between the horizontal temperature gradient and the vertical gradient (shear) of the geostrophic wind |
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Term
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Definition
| Vector difference or shear between geostrophic winds at two different levels |
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Term
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Definition
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Term
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Definition
| Momentum of a body in rotation (m x Vt x r) |
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Term
| Conservation of Angular Momentum |
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Definition
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Term
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Definition
| Measaure of the rotation of a fluid about a vertical axis relative to the Earths Surface ("+" is cyclonic "-" is anticyclonic) |
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Term
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Definition
| Shear is such that winds at different radii sweep out identical angular velocities as if fluid were rotating as a solid body (like a wheel) |
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Term
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Definition
| Sum of relative vorticity and planetary vorticity (as quantified by the coriolis parameter) |
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Term
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Definition
| Absolute vorticity divided by the depth of a column of rotating air |
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Term
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Definition
| Constant potential temperature |
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Term
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Definition
| Surface of constant potential temperature. Temperature of air along isentropic surface is changing at the dry adiabatic rate which means that its potential temperature is not changing at all--its constant |
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Term
| Isentropic Potential Vorticity (IPV) |
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Definition
| Potential vorticity measured on an isentropic surface |
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Term
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Definition
| Large scale north-south meanders in the jet stream, also known as Rossby waves or long waves |
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Term
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Definition
| Number of planetary waves circling globe at a given time |
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Term
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Definition
| Changes in the planetary vorticity must be compensated by changes in the relative vorticity and planetary waves develop |
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Term
| Intrinsic Phase Speed (Co) |
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Definition
| Speed of planetary wave propagation relative to the mean zonal wind |
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Term
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Definition
| Speed of planetary wave propagation relative to the ground, typically west to east |
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Term
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Definition
| Different wavelength waves move at different instinsic phase speeds, so they separate or "disperse" |
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Term
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Definition
| Changes in the planetary vorticity and the column depth between isentropic surfaces as quantified by the static stability must be compensated by changes in the relative vorticity and planetary waves develop |
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Term
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Definition
| Waves that tend to grow the fastest under conditions of baroclinic instability |
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Term
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Definition
| When a disturbance is imposed on either the wind of the pressure field, the other field adjusts to reach a new geostrophic balance |
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Term
| Internal Rossby Radius of deformation |
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Definition
| distance at which the magnitude of the geostrophic adjustment reduces to a value of 1/e of its original value at the location where the disturbance was imposed |
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Term
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Definition
| spatial distribution of pressure on a constant altitude chart, or height on a constant pressure surface |
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Term
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Definition
| Warm air rises, poleward aloft. Cold air sinks, equatorward at surface. |
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Term
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Definition
| Warm air forced to sink, cold air forced to rise (Ferrel cell dominant in mid-latitudes) |
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Term
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Definition
| Spiral traced by the tip of wind driven current vectors in the top layers of the ocean |
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Term
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Definition
| Produces upwelling along the west coasts of continents |
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Term
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Definition
| Body of air with well defined characteristics, usually of moisture content and temperature |
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Term
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Definition
| Boundary between two different air masses |
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Term
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Definition
| Horizontal spreading of air |
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Term
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Definition
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Term
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Definition
| Semi-permanent boundary between the warm and cold air masses (in reality not really contiguous) |
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Term
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Definition
| Weather measurements taken at the same time |
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Term
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Definition
| Line of equal potential temperature |
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Term
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Definition
| Region of packed isentropes showing strong potential temperature gradients |
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Term
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Definition
| The inversion that forms due to the cold air sliding under the warm air; temperature warms rapidly with height |
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Term
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Definition
| Air above flows down the sloping frontal surface |
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Term
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Definition
| Air above flows upward along the sloping frontal surface |
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Term
| External Rossby-Radius of deformation |
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Definition
| "Spillage" distance of a front from its starting location to the point where it comes into geostrophic equilibrium |
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Term
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Definition
| Increase in the strength of a horizontal temperature or potential temperature gradient |
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Term
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Definition
| Physical processes that compress temperature gradients |
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Term
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Definition
| Pertaining to passive advective effects of the wind field without consideration of forces |
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Term
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Definition
| Air streams coming togeher or slowing down along the direction of flow (isotherms become more tightly packed) |
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Term
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Definition
| Change of wind speed across direction of flow (changes orientation of isotherms causing them to compress) |
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Term
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Definition
| Differential vertical motion moves vertical potential temperature gradients into the horizontal |
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Term
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Definition
| Weakening or dissipation of a front through weakening the horizontal temperature gradient |
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Term
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Definition
| The component of the actual wind that deviates from a geostrophic wind value |
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Term
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Definition
| Temporary cross-frontal circulation also with rising and sinking motions that occurs during geostrophic adjustment near a front. |
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Term
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Definition
| Three air mass frontal systems (warm, cool and cold) where one of the fronts rides up over the coldest mass |
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Term
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Definition
| Three air mass frontal system where the coldest air is behind the occluded front (occluded front at surface looks like an extension of the cold front) |
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Term
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Definition
| three air mass system where the coldest air is ahead of the occluded front (looks like an extention of the warm front) |
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Term
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Definition
| Front at the jet stream core associated with a fold or break in the tropopause |
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Term
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Definition
| Location at the jet stream where transverse ageostrophic circulations extrude stratospheric air into the troposphere, wrapping the tropopause around the jet core |
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Term
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Definition
| Boundary of dry mixed-layer/residual layer air from the semi-arid plateaus of Northern Mexico and Southwestern US, and the maritime tropical to the east |
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