# What are the main sources of nitrogen oxides in the atmosphere?

Oct 15, 2016

Lightning and emissions from combustion engines

#### Explanation:

Localised areas of high temperatures allow atmospheric nitrogen and atmospheric oxygen to react and form nitrogen oxides, such as $N O$ and $N {O}_{2}$.

${N}_{2 \left(g\right)} + {O}_{2 \left(g\right)} \to 2 N {O}_{\left(g\right)}$

Most $N O$ formed typically further reacts with atmospheric ${O}_{2}$ to form $N {O}_{2}$

$2 N {O}_{\left(g\right)} + {O}_{2 \left(g\right)} \to 2 N {O}_{2 \left(g\right)}$

• High temperature may result from lightning, causing atmospheric nitrogen and oxygen to react
• High temperature combustion chambers in combustion engines or power plants may result in the formation of nitrogen oxides
• Exhaust typically releases $N O$ and $N {O}_{2}$ in a ratio of $4 : 1$