  The Venusian atmosphere is covered by clouds with super-rotating winds whose
accelerating mechanism is still not well understood. The fastest winds,
occurring at the cloud tops ($\sim$70 km height), have been studied for decades
thanks to their visual contrast in dayside ultraviolet images. The middle
clouds ($\sim$50-55 km) can be observed at near-infrared wavelengths (800-950
nm), although with very low contrast. Here we present the first extensive
analysis of their morphology and motions at lower latitudes along 2016 with
900-nm images from the IR1 camera onboard Akatsuki. The middle clouds exhibit
hemispherical asymmetries every 4-5 days, sharp discontinuities in elongated
"hook-like" stripes, and large contrasts (3-21%) probably associated with large
changes in the optical thickness. Zonal winds obtained with IR1 images and with
ground-based observations reveal mean zonal winds peaking at the equator, while
their combination with Venus Express unveils long-term variations of 20 m
s$^{-1}$ along 10 years.
