Cloud streets are seldom recognised from the ground because of the scale of them. They were only seen as a distinct cloud form in satellite photos, and as far as I know, that is the only way to positively recognise them. From the ground it just looks like a sky of cumulus, some taller than others. Those (again) are altocumulus undulatus. They are fairly obviouslt aligned perpendicular to the wind direction. There is a layer of other cloud below - cumulus fractus - so that perspective give you the clue that the altocumulus is much higher. Typically, altocumulus, being a "middle cloud" is somewhere in the range of 7,000 to 24,000 (roughly). Once you recognise the cloud type, you have a bit of an idea on the height. In Christine's photo, I reckon the ac is at about 12,000 feet.