Under what conditions does Kelvin-Helmholtz instability occur?
The Kelvin–Helmholtz instability occurs when there is a velocity shear at the interface between two fluid layers.
What causes Kelvin-Helmholtz?
An extremely rare phenomenon, where a cloud produces a billowing wave pattern. They occur when there is a strong vertical shear between two air streams, causing winds to blow faster at the upper level than at the lower levels.
What are the requirements for Kelvin-Helmholtz waves?
Kelvin-Helmholtz waves are vertical waves in the atmosphere generated by wind shear. If enough moisture is present, a characteristic cloud, the Kelvin-Helmholtz wave cloud (also known as Fluctus), can be formed.
How do Kelvin-Helmholtz waves form?
Kelvin-Helmholtz waves form when winds move faster at the top of a cloud’s layer than the bottom. This difference in wind speed or direction is called wind shear. Faster moving air at the top of the cloud scoops the top of the cloud layer forward, producing a striking wave-like pattern up in the sky.
What is the Kelvin Helmholtz timescale?
In astrophysics, the thermal time scale or Kelvin-Helmholtz time scale is the approximate time it takes for a star to radiate away its total kinetic energy content at its current luminosity rate.
What is Barotropic instability?
Barotropic instability is a wave instability associated with the horizontal shear in a jet-like current. Barotropic instabilities grow by extracting kinetic energy from the mean-flow field. Baroclinic instability, however, is associated with vertical shear of the mean flow.
How rare are Kelvin-Helmholtz waves?
Kelvin-Helmholtz are known as wave clouds and are not common to see in Florida. They’re actually rare anywhere. Clouds can develop this wave shape when there is a difference in air density and when the air above is moving more quickly than the air below.
What is the Kelvin-Helmholtz timescale?
Which part of stellar evolution does the Kelvin Helmholtz time describe?
The Kelvin–Helmholtz timescale describes the duration of the contraction phase of a star when it (temporarily) runs out of nuclear fusion.
What is the difference between baroclinic and barotropic?
In meteorology a baroclinic flow is one in which the density depends on both temperature and pressure (the fully general case). A simpler case, barotropic flow, allows for density dependence only on pressure, so that the curl of the pressure-gradient force vanishes.
What is baroclinic instability?
Baroclinic instability refers to a process by which perturbations draw energy from the mean flow potential energy. The conversions of energy are proportional to perturbation heat fluxes in both horizontal and vertical directions.
Why don t stars collapse under the weight of their own gravity?
A star’s life is a constant struggle against the force of gravity. Gravity constantly works to try and cause the star to collapse. The star’s core, however is very hot which creates pressure within the gas. This pressure counteracts the force of gravity, putting the star into what is called hydrostatic equilibrium.
What keeps a star from collapsing under its own gravity?
Stars are fueled by the nuclear fusion of hydrogen to form helium deep in their interiors. The outflow of energy from the central regions of the star provides the pressure necessary to keep the star from collapsing under its own weight, and the energy by which it shines.
What is barotropic instability?
What are jellyfish clouds?
These unusual, but not entirely uncommon clouds along the Central Coast are known as jellyfish clouds or Altocumulus Castellanus. These are typically middle level clouds that are classified as altostratus or altocumulus, which form at altitudes from 6,500 to 23,000 feet. They are primarily composed of water droplets.
What are popcorn clouds?
Cirrocumulus. Cirrocumulus clouds are fairly rare and fun for enthusiasts to discover. They are commonly called “popcorn” clouds because they look like thin white popped kernels floating high in the sky.