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Most volcanoes occur where subduction is taking place, that is when one plate is subducting under another.

When the subducting plate gets to a certain depth, it loses water content and this helps to melt the mantle rocks around it. This magma can sit in the mantle for sometime as it goes towards the surface.


As the other user suggests, there are lots of volcanoes around the Pacific Ring of Fire. This is true, but the reason for that is there is a lot of subduction going on around the perimeter of the Pacific.

The other place you can get volcanoes is over hot spots. Hot spots are plumes of molten rock that shoot magma into the crust and form volcanoes. Check out How will plate tectonics change the future? for an explanation about hot spots.


OK ... not simple, but here goes.


I’ll explain a bit about the Sun, then a bit about the Earth, then put it all together.

The sun, whilst it appears to be a gently warming & beneficial, yellowish orb that reappears regularly (unless you live where I do) is actually an unconstrained nuclear fusion reaction of screaming intensity. The power it puts out as radiation is literally unimaginable.

Along with electromagnetic radiation of all frequencies, it also continually emits a stream (doesn’t convey the intensity I’m after, try torrent) of charged particles out into space. These charged particles are particularly intense when there are many sunspots. [It seems to have an 11 year cycle, but I’ll leave that bit.]

Next we need to understand our side. The earth’s outer core is a molten liquid, rich in iron. Due to the heat released by nuclear decay (predominantly in the inner core) there are strong convection currents circulating it. Recent evidence (https://phys.org/news/2016-12-satellites-jet-stream-earth-core.html) suggests this motion is much more energetic than previously thought. The motion of this conducting fluid gives rise to our magnetic field, which extends outwards into space. This is the magnetosphere, the region of space where earth’s magnetic field dominates that of the Sun.

When these charged particles emitted by the Sun, moving at millions of metres per second, collide with the earth’s magnetic field they are made to spiral in towards the poles. As they descend, still moving at tremendous velocities, they collide with atoms and molecules in the atmosphere.

This enetgises the molecules (lifts their electrons into higher orbits) and as they tumble back down, the electrons’ energy is released as light. If the molecule happens to be nitrogen (it often is, as nitrogen makes up about 78% of the air) then a red, violet or blue colour is seen. Oxygen molecules (the majority of the remaining atmospheric particles) tend to produce green or yellow colours.

Here’s the mechanism:

enter image source here

Taken from: http://earthsky.org/earth/what-causes-the-aurora-borealis-or-northern-lights

The whole show appears from the surface of the earth like curtains wafting in a breeze. I’m told it is exceptionally beautiful, but despite years of trying, have yet to see it.


6 things


I will give you all the requirements, not just the weather ones.

1)Warm water. A sea temperature of 26.5 degrees C is required. I was never sure why it was exactly 26.5 degrees, or if you would get a hurricane with sea temperatures of say 25.8 degrees, but in any event that is the number we (meteorologist) refer to. This is required to get water vapor into the lower atmosphere to begin cloud formation.

2)Coriolis force. You do not get hurricanes at 5 degrees latitude or less as the Coriolis force is not strong enough to form a low pressure center of any significance. You rarely get hurricanes between 5 and 10 degrees latitude.

3)Low vertical wind sheer. This basically means the winds are relatively uniform with altitude. This allows vertically developing cloud to grow without being "blown" over. Otherwise this happens:

enter image source here

4)Instability. The atmosphere has to be unstable, encouraging vertical cloud development (convection).

5)Mid level humidity. You need moisture at the surface to start convection and cloud development and you need moisture at mid levels to continue the development to very high altitudes.

6)A focus disturbance. You need a point for the hurricane to start. It can be a low pressure center, or a front or an atmosphere wave or really any sort of disturbance in the atmosphere.

The page that the above image is on actually has more pictures. I think my explanations are a bit easier to understand but go there and see what is says and judge for yourself.



Vibrations that move through the ground carrying the energy released during an earthquake are called #seismic  waves.#


Here is what Science Daily says about seismic waves:

Seismic wave
A seismic wave is a wave that travels through the Earth, most often as the result of a tectonic earthquake, sometimes from an explosion.

There are two types of seismic wave
(body waves and surface waves)

1) Body waves (also have two types)
#color(white)(..)# Primary (P-waves)
#color(white) (..)# Secondary (S-waves)

2) Surface waves
Surface waves are analogous to water waves and travel just under the Earth's surface. They travel more slowly than body waves.

~ ~ ~ ~ ~ ~ ~ ~

Here's information about seismic waves from an on-line study guide

Seismic Wave:
⚡ Seismic waves are vibrations that travel through Earth carrying the energy released during an earthquake.

⚡ They carry energy from an earthquake away from the focus, through the Earth's interior and across the surface.

P Wave:
⌁ The first waves to arrive from the earthquake are "Primary Waves."

⌁They are seismic waves that compress and expand the ground
like an accordion.

⌁ They can move through solids & liquids.

S Waves:
⌁ After P Waves come the "Secondary Waves."

⌁ They are seismic waves that vibrate from side to side as well as
up and down.

⌁ They shake the ground back and forth.

⌁ They can't move through liquids, just solids.

Surface Waves:
⌁ When P and S waves reach the surface, some become surface waves.

⌁ They move more slowly then P & S waves, but produce severe ground movements.

⌁ They move the ground like ocean waves and shake buildings side to side.

Question #25584

Ms. Worth
Ms. Worth
Featured 4 months ago


High altitude, high velocity winds are called #"jet streams."#


According to actforlibraries.org

  • Jet streams are very fast moving currents of air found at about 10 km (6.2 miles) above the surface of the earth.
  • The major jet streams usually follow an undulating narrow path from west to east.
  • There are jet streams on both sides of the equator.
  • Jet streams close to the poles are called polar jet streams
  • Those at the tropics are known as subtropical jet streams, which are weaker than the polar jets.
  • Jet streams form due to the orbital rotation of the planet, along with atmospheric variations in temperature, which produces strong winds.

Here is an image of the jet streams

enter image source here

Here's an AccuWeather illustration of how the jet stream brought the ultra-cold weather down from the Arctic to the eastern United States in the last few weeks

enter image source here


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