Electromagntic wave, such as an X-ray.
Explanation:
- Electromagnetic wave does not require any medium to travel. These waves propagate outwards from the source.
- They can travel even through the vacuum of outer space.
- The major source is the sun which emits radiation in the form of the Electromagnetic spectrum.
- These waves travel through oscillating electrical and magnetic fields generated by the oscillating charged particles.
- These waves oscillate in the perpendicular direction of planes concerning each other and are in form.
- Electromagnetic waves travel at speed of light.
The sun hits bodies of water (ponds, oceans, pools, puddles) and it evaporates into a gas known as water vapor which goes up and forms a cloud. When the cloud gets heavy the water condensates back into little droplets and falls back to the ground. This is rain.