What is a tidal wave?

 

Destructive Waves

A tidal wave is a large ocean wave, usually caused by an earthquake or violent storm at sea. 

Sometimes great, destructive waves sweep in from the sea like a huge tide.  Most people call these “tidal wave,” but they have nothing to do with true waves.

Scientist have a special name for tidal waves.  They call them “tsunami” (pronounced su NA me), a Japanese word that means “storm waves.”

A tidal waves, or tsunami, is not like ordinary ocean waves along the seashore.

A tidal wave, or tsunami, is not like ordinary ocean waves along the seashore.

A tidal wave can start when an earthquake or volcanic eruption or violent storm takes place far out in the ocean.

The waters above the spot are violently stirred and great wave is set in motion.  When a tidal wave very low tide.  Then the great wave comes crashing in as a solid wall of water.  Some are so big that they can destroy whole villages.  Often, the waves are so small they cause no damage at all.

Photo courtesy:  newprophecy

What makes an ECHO?

Echo

If you shout or clap your hands in a canyon, the sound may make an echo.  An echo is a sound that we hear after it is reflected, or bounced back, from some large obstacle. 

When you call out in a canyon, the sound waves of your voice travel through the air in all directions.  Some of the sound strikes the hard, smooth surface of the canyon wall and comes bouncing back like a rubber ball.

A moment later, these reflected sound waves reach your ears, and you hear an echo of your voice.

The sound waves may bounce from wall to wall, producing several echoes.

Echoes don’t last forever.  An echo becomes fainter each time until, finally, you can no longer hear it. 

An echo isn’t clear in a large room because the sound bounced back so quickly from  the walls and ceiling that it mixes with the original sound.  You just hear extra noise.  That’s why big, empty rooms are often noisy.

Visual source: seed

What causes waves?

Waves

Water waves are caused mainly by the wind.  On a windy or stormy day there are many waves in the water, and on a calm day there are fewer waves.  

This explains what makes most waves in the water.  Winds push up waves on seas, lakes and ponds.  The waves you see on a calm day were started far away.  Somewhere over the ocean winds blew against the water and set it in motion. 

When you watch the waves, the water seems to move forward.  But the water does not actually move forward in a wave at all.  A water wave is mostly the up-and-down motion of the water.  This may be compared to the waves made in a rope by shaking one end of it.  The waves un the length of the rope, but the rope does not move forward. 

When the wave motion of the water reaches the shoreline, the shallow bottom makes the water spill onto the beach.  Sometimes an earthquake or an undersea volcano causes a great, destructive wave to seep in from the ocean like a huge tide.  Most people call these tidal waves.  Scientist call them “tsunami” (su NA me), Japanese word that means “storm wave”.

Photo source:  maui

What is a Quasar?

  

Quasar

The mysterious quasars (KWAY sahrs) are intensely bright, star like objects on the edge of the universe.  One of the big mysteries about the quasars is what they are.  Not stars and not galaxies (groups of stars), quasars have baffled scientists since they were discovered in the early 1960s.  A quasar is many times brighter than an entire galaxy and a strong emitter of radio waves.  When first discovered, scientists called them quasi-sellers, meaning “somewhat star like” radio sources.

 

The  name was later shortened to “quasar.”  One thought is that a quasar is a kind of super atomic furnace, too hot to be solid.  It is a huge ball of gases that glow with a brilliant light and sent out strong radio signals.  A typical quasar may be millions of times bigger and brighter that the sun.  Quasars are so far from the earth that they can only be seen through the largest telescope.

 

Photo courtesy:  fascinatingly