“Pycnocline” is a term related to:

Correct answer: Sea-water density. A pycnocline is the layer in the ocean where the density of seawater changes quickly with depth.

Background: Density changes with temperature (thermocline) and salinity (halocline).

• Ocean relief: Ocean relief refers to the shape of the seafloor, not density layers.
• Development of coral reef: Coral reef development is a different topic.
• Mesosphere: The mesosphere is a layer of the atmosphere, not of the ocean.

Did you know? The Greek word pyknos means “dense”.

Memory trick: Pycno = density.