Rails are no longer visible above the clouds

Summary:

I'm a little bit confused. There is a rail on the oak plank but I cannot see it above the clouds.

Observed Results:
I cannot see the rail above the clouds.

Expected Results:
I can see the rail even I am above the clouds.

Suggest Debug Ways:

I think Mojang can make the clouds as a half-transparent block that everyone could see the rail. This way also let the map creators design the shape of the clouds.

Steps to Reproduce:

1.Go 2 blocks under the clouds and type:

/setblock ~ ~ ~ iron_block 

in chat. (You can set any block you want instead of iron block)

2.Place a rail or powered rail or detector rail activator rail on it

3.Go above the clouds, you cannot see the rail.