Two questions which arises in my mind about aurora borealis are:
Why does aurora borealis occur?
Why does aurora borealis occur in a particular time of the year?
Answers:
As solar wind approaches the Earth, it meets the Earth's magnetic field. In the ionosphere, the ions of the solar wind collide with atoms of oxygen and nitrogen from the Earth's atmosphere. The energy released during these collisions causes aurora borealis.
Aurora borealis is active the whole year. Since it needs to be dark in order to see aurora borealis in the sky, late August/September through the very beginning of April is the best time to go to a destination located in the aurora zone for a chance to see them.
Note: These are the questions which arises in my mind only. It may differ from person to person.
A frame structure is a structure made up of many rigid parts joined together to form a 'framework'. These different parts are called members. Shell Structures. A shell structure is more enclosing than a frame structure - it surrounds and encloses something.
Este material añadido caliente se enfría por conducción y convección de calor. En los bordes de consumo de la placa, el material se ha contraído térmicamente hasta volverse denso, y se hunde bajo su propio peso en el proceso de subducción, generalmente en una fosa oceánicase. es verdadero
