Outflows

Outflows are flows of material, energy, or information that move away from a defined system boundary. They are the counterpart to inflows and are studied across disciplines to understand how systems lose mass, momentum, or energy and how these losses affect evolution and environment.

In astronomy, outflows include protostellar winds and collimated jets driven by accretion onto young stars, as well as winds and jets from active galactic nuclei. They can remove angular momentum, regulate accretion, and drive shocks into surrounding gas. Observables include molecular emission, forbidden lines, and synchrotron radiation; speeds range from tens to thousands of kilometers per second, and outflows may be highly collimated or more wide-angled.

In meteorology and atmospheric science, convective outflows are air masses that spread out from thunderstorm cells, forming outflow boundaries that influence weather development over downstream regions. In hydrology and engineering, dam outflows or reservoir releases describe water intentionally discharged to manage storage, flood risk, or ecological needs; natural outflows include rivers draining into seas and groundwater discharge.

In broader terms, outflows affect the energy and matter balance of systems, influence surrounding environments, and interact with inflows in complex cycles. Studying outflows involves measuring fluxes, velocities, composition, and energy transfer, as well as modeling the driving forces and boundary conditions that sustain them.