Atmospheric aerosols

Question 1

Typical concentrations (/cm^3 and micrograms/m^3) of particles in arctic, city (europe), rural Europe), ocean and Santiago

Answer 1

Arctic: 10-100, 0-1 City: 1000-100000, 10-100 Rural: 500-5000, 1-100 Ocean: 100-1000, 1-10 Santiago: ?, 10-1000

Question 2

Primary particle sources

Answer 2

Breaking of waves (<100nm), Resuspension of soil dust (Most mass in the coarse fraction (1-10 µm), but also significant in fine fraction (0.1-1 µm).), Abrasion by vehicles: Road surface, tyres, brakes (large particles), and Combustion (coal, gas, oil, domestic biomass, forest fires) (soot: 30-200 nm, hydrocarbons: 1.5-30 nm), volcanoes, biological particles.

Question 3

Volatility

Answer 3

Tendency of a gas to condensate on particles. Low volatility want to condensate.

Question 4

Two sources of particles in the atmosphere

Answer 4

Primary particles (Directly from source) and secondary particles (gas to particle conversion)

Question 5

Secondary particle formation. Two types

Answer 5

• Condensation of gases on pre-existing particles, so called secondary formation.
• New particle formation (or nucleation) of new particles from gaseous precursors.

Question 6

Mechanically generated primary particle sources

Answer 6

Breaking of waves, vehicle abrasion, and grinding

Question 7

Primary particles from combustion, sources.

Answer 7

Volcanoes, forest fires,domestic biomass, coal power plant, biomass power plant, vehicles.

Question 8

Secondary particle formation, sources

Answer 8

Forest emission, combusted gases, oceanic biota, pack-ice

Question 9

Secondary particle formation by nucleation, sources

Answer 9

sulfur sources, ammonia sources, organic sources

Question 10

Breaking of waves

Answer 10

ocean spray when waves break. Water evaporates from droplets in the air. Salt and biological particles are created.

Question 11

Wind blown dust

Answer 11

Larger particles are blown over the ground, to heavy to lift, Saltation. Sparks movement of other particles that can be airborne

Question 12

Diesel exhaust

Answer 12

Soot particles released from combustion in engine. After the exhaust pipe cooling causes organic and sulfur to condense on the particles.

Question 13

Transport between upper and lower troposphere time

Answer 13

about 1 month

Question 14

Transport between stratosphere and troposphere time

Answer 14

can take years

Question 15

Transport time around the globe

Answer 15

two weeks

Question 16

Two types of wet deposition

Answer 16

1. In-cloud scavenging (or rainout), where CCN are activated and falling out as rain (nucleation scavenging) and where aerosol particles are impinging on falling rain droplets.
2. Below cloud scavenging (or washout), where aerosol particles impinge on falling rain droplets below the cloud.

Wet deposition 80-85% of particle removal from atmosphere.

Question 17

Three ways of impinging

Answer 17

Brownian motion, impaction and interception

Question 18

Dry deposition

Answer 18

Particles deposit to the grown or objects to the grownd by gravity. No water involved.