Divergence occurs when a stronger wind moves away from a weaker wind or when air streams move in opposite directions. When divergence occurs in the upper levels of the atmosphere it leads to rising air.
Which side of an upper-level trough divergence is found?
Typically, divergence is found on the front (eastern) side of the trough, and convergence on the back (western) side. In the figure at right, the upper-level trough is shifted westward from the low pressure center at the ground.
Where does divergence aloft typically occur relative to an upper-level trough?
The strongest divergence aloft occurs on the northeast side of the trough, where a surface low pressure tens to develop. The strongest convergence aloft occurs on the northwest side of the trough, where a surface high pressure tends to develop.
Are high pressure area convergent or divergent?
Surface high pressure systems in the Northern Hemisphere have a clockwise rotation with wind turning slightly outward away from the highest pressure. This causes air to diverge, or move away, from the center of the high near the ground.
How does upper-level divergence create clouds?
While air swirls inward and converges into the center of surface low pressure, an “upper-level disturbance” causes divergence aloft that allows air columns to shed weight. The end result is rising air, and usually clouds and precipitation associated with a low.
What happens when the upper-level divergence of air is greater than the lower level convergence of air in a storm?
When upper-level divergence is stronger than lower-level convergence, more air is taken out at the top than is brought in at the bottom. Surface pressure drops, and the low intensifies, or “deepens.”
How are upper-level divergence and surface lows related?
What causes divergence aloft?
Divergence aloft is associated with rising air throughout the troposphere, which is associated with low pressure and convergence at the surface. Convergence aloft is associated with sinking air throughout the troposphere, which is associated with high pressure at the surface and thus divergence at the surface.
Why strong upper level divergence will cause the pressure in the Centre of a surface low to decrease?
Divergence is removing more air than is being added by surface convergence. The surface low pressure will decrease. The decrease in surface pressure will cause the converging surface winds to blow faster.
When convergence occurs in the upper atmosphere it causes?
A convergence zone in meteorology is a region in the atmosphere where two prevailing flows meet and interact, usually resulting in distinctive weather conditions. This causes a mass accumulation that eventually leads to a vertical movement and to the formation of clouds and precipitation.
What are 3 reasons air rises?
Surface heating and free convection. During the daytime, the earth’s surface is heated by the sun, which in turn heats the air in contact with the surface.
What does upper-level convergence cause?
Convergence aloft, caused by increasing vorticity, promotes sinking air, and surface high pressure. Upper-level divergence causes the formation and intensification of surface mid-latitude cyclones. Upper-level convergence causes high pressure at the the surface.
What is the upper level trough called?
upper-level trough. A pressure trough existing in the upper air, but sometimes restricted to the troughs that are much more pronounced aloft than near the earth’s surface. Also known as high-level trough; trough aloft; upper trough.
What are some examples of upper level divergence patterns?
The two best examples of upper level divergence are PVA and divergence associated with the right rear and left front quadrants of a jet streak. Upper level diffluence by itself does not cause rising air. An upper level diffluence pattern by itself does not cause rising air. It is upper level divergence that causes rising air.
What causes upper level wind divergence in the jet stream?
Upper-level troughs in the jet stream (as shown in diagram) reflect cyclonic filaments of vorticity. Their motion induces upper-level wind divergence, lifting and cooling the air ahead (downstream) of the trough and helping to produce cloudy and rain conditions there.
How to measure the strength of convergence or divergence aloft?
The strength of convergence or divergence aloft can best be captured by evaluating conditions at the LND. One of the most important measures of the potential of the upper levels to support convergence or divergence is vorticity. Divergence Versus Diffluence
