Embodiments are disclosed for terahertz spectroscopy and imaging in dynamic environments. In an embodiment, a method comprises using a sensor of an electronic device to determine an orientation of the electronic device. A transmitter of the electronic device emits an electromagnetic (EM) wave in a terahertz (THz) frequency band into a dynamic environment according to a power duty cycle that is determined at least in part by the orientation. A receiver of the electronic device receives a reflected EM wave from the environment. A spectral response of the reflected EM wave is determined that includes absorption spectra that is indicative of the transmission medium in the environment. The absorption spectra are compared with known absorption spectra of target transmission mediums. Based on the comparing, a particular target transmission medium is identified as being the transmission medium in the environment, and a concentration level of the identified target transmission medium in the environment is determined.