The Ionosphere

Question 1

Draw an electron density vs altitude for the ionosphere and indicating its regions

Answer 1

See notes.

Y-axis: height (km) (50 to 800)
X-axis: electron density (m^-3) (10^7 to 10^13)

D, E, F regions labelled.
Night and day labelled.
R=0, R=200 labelled. (**what is R lol)

Question 2

Define airglow

Answer 2

Airglow is continuous, weak, exists at all altitudes, and is driven by photons from the sun.

Question 3

Define aurora

Answer 3

Aurora is irregular in form and in its occurrence, it is more intense and is restricted to the poles. It is excited by the impact of energetic solar particles

Question 4

Illustrate the chemical reactions occurring in the Appleton layer (F-region)

Answer 4

This is where O+ is converted to other ions and undergo radiating recombination with electrons. Emission from excited atoms is called airglow.

O+ + O2 -> O2+ + O
O2+ + e- -> O* + O
O* -> O + hv

can also happen with nitrogen (N2 instead of O2 in first step)

Question 5

Illustrate the chemical reactions occurring in the Kennelly-Heaviside Layer (E-region)

Answer 5

Since the concentration of N2 is higher than that of all other species, one might expect N2+ to be the dominant ion.

However, NO+ and O2+ are found to be the dominant ones.

The reason for this is rapid charge transfer:

N2+ + O -> NO+ + N*
N2+ + O2 -> O2+ + N2

NO can be generated in situ from: O2+ + N2 -> NO + NO+

Since NO has a low ionization energy (9.3 eV), it acts as a sink for positive charge

Question 6

Illustrate the chemical reactions in the D-region (Formation from O2+)

Answer 6

Formation from O2+

O2+ + O2 + M -> O2+·O2 + M (clustering)
O2+·O2 + H2O -> O2+·H2O + O2 (ligand switching)
O2+·H2O + H2O -> O2+·(H2O)2 (clustering)
O2+·(H2O)2 + H2O -> H+·(H2O)2 + O2 + OH (intracluster reaction)

Question 7

Illustrate the chemical reactions in the D-region (Formation from NO+)

Answer 7

Formation from NO+

NO+ + N2 + M -> NO+·N2 + M (clustering)
NO+·N2 + H2O -> NO+·H2O + N2 (ligand exchange)
NO+·H2O + H2O -> NO+·(H2O)2 (clustering)
NO+·(H2O)3 + H2O -> H+·(H2O)3 + HONO (intracluster reaction)

Question 8

Illustrate the chemical reactions in the D-region

Answer 8

The D region contains the most complicated ions in the atmosphere.

They are mainly of the form H+(H2O)n – called protonated water clusters

Growth of water cluster ion:
H+(H2O)2 + H2O (+M) -> H+(H2O)3(+M)