Net radiation

The net radiation is the value of the body's own radiation. Since in a physical measurement of z. B. Infrared radiation (heat rays) cannot exactly differentiate between actual natural radiation and reflection , the net radiation can only be determined mathematically, namely if the body itself is also irradiated. ${\displaystyle R}$

The net radiation must be determined in order to be able to compare the radiation budget of the earth . It is calculated as the difference between the absorbed short-wave global radiation (with the albedo ) and the effective long-wave radiation : ${\displaystyle Q_{\text{g}}}$ ${\displaystyle a}$ ${\displaystyle A_{\text{e}}}$

${\displaystyle R=(1-a)Q_{\text{g}}-A_{\text{e}}}$

Depending on whether the absorbed global radiation or the effective radiation predominates, the net radiation can assume positive or negative values.

The net radiation of a place shows a diurnal variation: shortly after sunrise it becomes positive, reaches its maximum around noon, then decreases and around the time of sunset it takes on negative values. It also varies with geographical latitude: it is greatest in the tropics and decreases towards the poles. It is higher over the ocean than over the mainland , since ocean surfaces absorb more global radiation (lower albedo) and the counter-radiation over the oceans is higher due to the greater water vapor content of the air (clouds). Since the sea portion is larger in the southern hemisphere than in the northern hemisphere, the net radiation is also higher there.

See also

• climatology
• Greenhouse effect
• Abiotic environmental factors

Individual evidence

1. ↑ JL Monteith: Basic features of environmental physics . Steinkopff, 1978, ISBN 978-3-7985-0464-6 , p. 46 (with a general definition of surfaces).
2. ^ Alan H. Strahler, Arthur N. Strahler: Physical geography . UTB, 2009, ISBN 978-3-8252-8159-5 , section "Insolation", p. 88-89, 107-108, 115-118 .