Edit in Photoshop - Filesize

[vo5tr0]

Hey, 

Lightroom CC has the option to send my raw Photos over to Photoshop and edit them further. After closing this document it automatically imports everything as .tif file back to lightroom. 

Can someone explain to me, why this file gets so large? Even small edits (<10 layers) will blow this file up to over a gigabyte. Just opening a file in photoshop and saving it without ANY changes generates a 300mb+ file. 

The source raw dng image has around 25mb... How is that possible? 

Also I noticed, that my Desktop Lightroom CC randomly starts uploading the Original DNG File to the cloud again. Telling me the cloud version only holds a smart preview version. That's not true, though...

1. I downloaded the original from the cloud in the first place.

2. Doublechecking on android and iOS confirms an "Original DNG" in the cloud... 

[Rob_Cullen]

My 'simple' understanding:

RAW > RGB (TIF)

[RAW Mega-Pixels] x [3  RGB channels ] x [16bits / 8bits] x [Number of pixel layers in Ps] + [Adjustment layers].

And you might start to get the picture.