The reason for hearing the sound of whizzing in the columns of electricity or when we pass near the towers and high voltage lines high voltage power

Many of us are surprised to hear the sound of whizzing in the columns of electricity or when we pass near towers and high voltage lines .. What is the reason?
A lot of us surprised why we hear buzz (zszszs sound) when walking near high voltage power lines..what is the reason
There are two reasons for this whiz: -

1 - not to connect the transmission lines between them well, resulting in a flash-over between two points on the line between the difference of effort for a break in the isolation of the air between them.
2 - the phenomenon of Corona (Corona) or unloading Halli. This phenomenon alongside the sound of whizzing it occurs shows a bright, slanted, oblique glare and an interference with radio waves.
And the phenomenon of discharge corona (corona) is produced as a result of the causes of the most important

Corona is causes by the following reasons

1. The natural electric field caused by the flow of electrons in the conductor.

2. Interaction with surrounding air.

3. Poor or no insulation is not a major cause but increases corona.

4. The use of D.C (Direct Current) for. (Reason why most transmission is done in form of AC)
   And the occurrence of the phenomenon of discharge Corona (Corona) has significant damage to the transmission lines (transmission lines), which lead to increase the current of electricity very high and therefore to increase the temperature of the connector and increase losses and also cause the collapse of the insulators.
   Effects of Corona

5. line loss - loss of energy because some energy is used up to cause vibration of the air particles.

6. long term exposure to these radiations may not be good to health.

7. audible noise.

8. electromagnetic interference to telecommunication systems.
   5- ozone gas producton.

9. damage to insulation of conductor
   sorry about my english
   And to reduce the occurrence of this phenomenon (corona) by the work of the so-called bundle conductors in which to provide the area of ​​the connector section by making one connector is more than one conductor and then short circuit is done on these connectors