There is no doubt that there are thousands, maybe millions, of terminal velocity meteorites for every one that involves a hypervelocity impact. There are hundreds of thousands of meteors that have been recorded, and none have been observed to break up below about 20 km, and most much higher.zloq wrote:I think it's important to distinguish simplified models of typical scenarios from what can actually happen in the complex situation of a large object fragmenting at high velocity so that a chunk slams to the earth for immediate inspection - with or without a crater. I don't consider this straightforward and easily modeled with confidence, and I see words to that effect in the literature cited above. Therefore I consider "terminal velocity" an assumption that could easily be false - and I give the specific example of a high speed, low altitude fragmentation event.
The only certain example of a meteoroid reaching a very low altitude before breaking up is the Sikhote-Alin event in 1947. This was an iron body massing between 100 and 1000 tons, and some of the shrapnel produced when it broke up only 6 km high reached the ground at high enough velocities to create craters and embed itself in trees.
The only other historical high velocity impact I'm aware of was the Carancas (Peru) event in 2007. This was a stony meteoroid that survived all the way to the ground without breaking up at all- something previously considered impossible. People are still working to understand the nearly unique characteristics of that body.
In fact, there are some very good models now describing the behavior of meteors in the atmosphere. These models accurately describe the heating processes (including differential production of atomic species in the trail) and fragmentation processes. Asteroid 2008 TC3, which produced meteorites in Sudan, was modeled right to the ground, and the model accurately matched the actual strewn field, lending great support to the quality of this type of modeling.