What Am I?

I rolled by once again today
Darker now than yesterday
The more I move, the darker I get
Until my tears flow freely, and the ground becomes wet

The tears were not of woe, for sad I am not
Upon my head, the sun shines hot
Below me there are those that scamper about
Sometimes I turn on the light, and give a great shout

As the sun warms me, my tears do stop
The last one hits the ground, with a loud plop
I become whiter and whiter, and settle down
I suddenly become a white painted clown

I always become something different than before
I am now a lion with a great big roar
A lop-eared rabbit sitting next to a flower
A great blue whale in an ocean of power

Now I’m rolling by as a massive sub
Followed immediately by a small grizzly cub
The thinner I get, the brighter I am
Below I see the planet Earth, above me Jesus the Lamb

Below me I see the hospital, where John had a great fall
The patients wanted to help, alone I had to stand tall
All wanting to look up at me, floating proud
Have you guessed who I am? ...

(scroll down)
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      .
      
... I am a cloud