Climate investigation refers to earth-based observation. The nature of the body waves (P & S waves) of the earth's interior help understand the interior of the earth.

(i) Characteristics of P Waves:

© P waves (Primary waves) can propagate through all mediums (solid, liquid gas)

(ii) Characteristics of S Waves:

© S waves (Secondary waves) can travel only through solid medium.

This is why it is inferred that the inner core is solid.

(iii) Reason (Tilt) of the earth according to time of year:

[Diagram showing two circles representing Earth with sun rays, showing how sun's rays hit at different angles and heat distribution]

The sun hemisphere receives more heat, now the shadow zone gets more heat.

(iii) Understanding the interior:

(i) Since secondary waves cannot travel through outer core, and P-waves can be detected on other side of planet, it can be implied that the inner core is solid.

(ii) According to this is understood that pressure causes inner core to become cold despite high temperature.

Thus, shadow zone of a earthquake provides an indirect glimpse into the interior of the earth.