When we speak of greenhouses arch, we refer to polytunnel greenhouse model, because the structure of other types of greenhouses is flat, not arched. The shape of the arch is the one that defines the type of greenhouse.
The arch is the top of the truss but sometimes we refer to the truss as Arch name.
The arch is the part of the structure where the roof material is placed, which is mostly made of plastic.
Types of greenhouse arcs:
The rounded deck suppose a greater capacity to capture solar radiation on flat than pitched roofs.
Best evacuation of condensate on the cover and holds a greater volume of air than in the earlier covers.
Its aim is to improve light transmission, guiding due to the overhead position of the sun.
During winter months, tropical greenhouses have more uniform radiation and better spatial distribution than greenhouses with flat roof.
They lead to increased radiation interception of 5-6% (tropical greenhouses with less steep on south) 10% (tropical greenhouses steeper on south).
It also has higher resistance to inclement weather, specially in the case of strong winds when as a low risk from exposure to this from the other side when the greenhouses are properly oriented.
Pointed arc or gothic:
Its purpose is to improve light transmission with regard to semicircular arches, as they have greater ability to intercept sunlight.
Besides its shape allows them to keep greater volume of air and better evacuation of the condensate of the cover.