The interactions between the gospel of today and the traditions of the Exodus afford us to find suggestions in order to get the key about some enigmatic metaphors. For exemple, in verse Mt 17:5 a bright cloud overshadowed them … What kind of brightness can cast a shadow? The key is perhaps in Sinai. There too were strange “clouds”.
So, in Ex 19:16 the translations usually swallow an interesting description that is still kept by the masoretic text: ענן כבד. I do really think that a rather poor translation is to say just “thick cloud”, specially knowing about the emotions related to כבד, KaBoD, that theologically almost”technical” term which is related to the perceptible dimensions of the inmanent power of God. Remember Isaiah 6:3, please. Very few would have translated:
“Holy, holy, holy is the Lord Almighty;
the whole earth is full of his weight (or fat).”
The metaphorical connection between “glory of God” (kabod) and “cloud” is still clearer at the end of Exodus, in verse 4o:34.
Consequently in Mt 17 (Transfiguration text),the cloud of light is also “weighty”, it is to say, this cloud is the Kabod! …Or a symbol of it. So this cloud is able of everything, even of turning the light into shadow, building a protective umbrella over Jesus… later, taking him out of the “house of death” (the tomb).
As a matter of fact, reading the Syriac version of Mt 17:4, Peter wants to build three “roofs”, ܡܛܠܝܢ, word derived from the semantic root ܛܠ (shadow). But at the end of the day, without human hands, it is the “cloud” that ܐܛܠܬ (verbal form derived also from ܛܠ), expression that could be translated like “cast a shadow”… Possibly more effectively than Peter!