Analyzing gravity waves at the edge of space

[Elderberry]

Phys.org 7/30/2019

Jeff Forbes is working on a research project slated for the International Space Station (ISS) to help us better understand and forecast conditions on the edge of space.

NASA is funding the Atmospheric Waves Experiment (AWE) to analyze gravity (or "buoyancy") waves in a region of the upper atmosphere that can cause disruptions in radio and satellite communications as well as GPS—key tools for safe airplane and ship travel.

From its International Space Station perch, AWE will focus on colorful emissive layers in Earth's atmosphere, called airglow, to determine what combination of forces drive space weather in the upper atmosphere.

This region was once thought to be affected only by the sun's ultraviolet light and particles, but more recent analyses have shown that gravity waves generated by weather patterns on Earth are also having an impact.

More: https://phys.org/news/2019-07-gravity-edge-space.html

[Smokin Joe]

...gravity waves generated by weather patterns on Earth....

Weather on earth? More likely perturbation in the liquid core than storms on the surface.

But I see yet another tsunami of howling about "climate change".

[sneakypete]

How is it possible to measure gravity in a vacuum?

[Elderberry]

Not exactly "Gravity Waves". More like  Atmospheric Waves.

More info: http://www.physics.uwo.ca/~whocking/p103/grav_wav.html

1. Introduction

Most people are familiar with waves on the ocean surface. These arise at a density discontinuity between the water and the air, and exist because of the restoring force of gravity. Graphically, we can represent the density variation as a function of height as a step, with high density (water) low down, and lower density (air) higher up. This is shown in the next figure.

 But in fact, waves may occur in any medium in which the density decreases with height. If the restoring force is gravity, these waves are called gravity waves. Sometimes, they are called buoyancy waves, since their existence depends on buoyancy. Gravity waves can be thought of as an extension of a surface wave. The key requriement for such waves to exist is that more dense material must rise above less dense material, and then be restored by gravity.

So if a graph of density versus height looks like the following,

we will once again be able to sustain wave motions. Waves of this type exist throughout the atmosphere. They are actually called INTERNAL GRAVITY (or BUOYANCY) waves, to distinguish them from waves which occur at a surface interface.

Such waves can propagate and are important for
a) momentum and energy transport
b) turbulence production
c) they can trigger convection
d) they can significantly affect the atmospheric mean flow.

These waves can be generated in a variety of ways, but flow over mountains is one very common production method. This is shown in the next diagram.

More at link.

[rustynail]

Gravity waves cause things to fall off my desk.

[Elderberry]

Does the shoe fit?

It's Not My Fault. The Millennial Answer to Everything!

[Snarknado]

I think if authors are going to use the term gravity wave, they should clarify that it's completely unrelated to gravitational waves, especially now that LIGO has more or less proven the existence of the latter and threy're no longer just a theoretical possibility.

[Smokin Joe]

I think if authors are going to use the term gravity wave, they should clarify that it's completely unrelated to gravitational waves, especially now that LIGO has more or less proven the existence of the latter and threy're no longer just a theoretical possibility.

I almost got kicked out of a physics class for asking about the velocity of gravity. And I asked after class was over, definitely not in a disruptive fashion. ....

If it is an energy form, it has a rate of propagation.