Stratospheric Ozone

Question 1

What is the relationship between stratospheric Ozone and Global warming /cooling.

Answer 1

A thinner ozone layer does not directly lead to a warmer earth .

What does; when there is a lot of sunlight (UV radiation): then a thinner stratospheric layer contributes to the earth’ s increased absorption of UV leading to warming.

Global cooling : when there is a thin layer of stratospheric ozone then more IR escapes into space causing the earth’s surface to be much cooler than t needs to be .

Question 2

True or false: the cooling effect larger than the warming

Answer 2

True

Question 3

Why is there an increase in temperature ?

Answer 3

This is due to the absorption of incoming radiation.this raises the temperature and makes it warmer.

Question 4

Structure of the atmosphere

Answer 4

Troposphere: which is the lowest layer of the atmosphere closest to earth’s surface . Here temperatures decreases with altitude.this layer contains water vapor and vertical mixing .

Tropopause eg: the layer that separates the troposphere from the stratosphere. Here temperature stops decreasing with altitude and remains constant or begins to increase.

Stratosphere: from the tropopause to the stratopause .here temperature increase because it contains the ozone layer which absorbs UV.

The layers above the stratospher mesosphere (strtopause to mesopause) and then the thermosphere

Question 5

What are the radiation differences between the troposphere and the stratosphere?

Answer 5

The troposphere contains a lot of GHG absorbed from the erath’s surface . These GHG contribute to green hous effect where they absorbed IR from the earths surface and reemit it back onto earth n. This keep earth as a habitable place.

The stratosphere: this is where the Ozone layer is found which absorbs the UV radiation form the sun . Particularly the harmful ones UV-B and UV-C wavelengths.

Question 6

Which of the layers of the atmosphere is responsible for weather and climate

Answer 6

The troposphere is because of it nature .

Question 7

How do both the troposphere and stratosphere play a follow in climate change .

Answer 7

The troposphere contains the green house gases which are the main drivers for climate change.

The stratosphere contains the ozone layer which when depleted by ozone depletion substances has a complex relationship with radiation balances in earth.

Question 8

True or false : Ozone concentration is many times higher than it is here in the troposphere.

Answer 8

True . Because it contains the ozone layer

Question 9

Explain why we have the ozone layer

Answer 9

The ozone layer is formed as a result of the constant creation and destruction of the ozone in the stratosphere creating a layer at peak concentration.

Question 10

How is Ozone formed ?

Answer 10

The ozone layer is primarily formed from photochemical reactions.

The UV radiation from the sun splits Oxygen molecules into single atoms , theses atoms the bond with Oxygen molecules that were not broken down by radiation and the from Ozone(O3)

Question 11

True or false : photolysis (break down of molecules) is faster for both O2 and O3 molecules at higher altitudes. Motivate your answer .

Answer 11

True . Photolysis of O2 is faster with wavelengths shorter than 200nm and photolysis of O3 is faster with wavelengths shorter than 290nm which can only be found at higher altitudes.

Question 12

True or false : at less altitudes less Ozone is formed .

Answer 12

That is true

Question 13

What is a Dobson unit ?

Answer 13

This is a unit used to measure how much Ozone is in the air , from the top your head to the top of the atmosphere.

Question 14

Why is the Dobson Unit relevant ?

Answer 14

1. It helps to quantify ozone : it does this by providing a standard way of measuring and comparing ozone levels in the air. Tween different locations over time.
   2.helps to track and monitor ozone depletion caused by human activity.
2. It also helps to track the effectiveness of international policies and agreements Ike the Montreal protocols which aims to repair the the ozone layer .

Question 15

What are the critical molecules that usually cause the destruction of Ozone ?

Answer 15

NO, CL(can destroy a lot of ozone), Br( very potent in destroying o3),H,OH,NO2

Question 16

Ozone depleting substances .CFC

Answer 16

One them is chlorofluorocarbons, the resided in troposphere , have a life span of 100years, takes 5-10 years to reach the stratosphere where they take residence above the ozone layer photons with short wavelengths split them in to CL , etc. where they destroy O3 molecules.

Question 17

The different categories of ODS’s .

Answer 17

Hydro chlorofluorocarbons
Chlorofluorocarbons
Bromochloromethane
Halons
Nitrous oxide
Methyl Bromide
Carbon tetrachloride
Hydrobromofluorocarbons

Question 18

What are Ozone depletion substances?

Answer 18

This is the measure of how much damage a substance can do to the ozone layer in comparison to another substance

Question 19

What are some chemicals with high ODP’s

Answer 19

CFCs ( we’re used in refrigerators, air conditioning)
Halons : we’re used in fire extinguisher
HCFCS: they’re were developed as transition elements for CFCs

Many where used as propellants,cleaning solvent for surfaces..etc.
., for medical sterilization?

Question 20

What are some of the key factors that influence ODP

Answer 20

1. Atmospheric lifetime : the longer the lifetime te mor likely it is to travel to the stratosphere to destroy O3 molecules
2. Stratospheric catalytic activities: this is a substance potential to release Halons (CL , Br (Bromine)) which have high reactability and easily destroy O3 molecules

Question 21

What is the Ozone hole ?

Answer 21

This is the thinning of the ozone layer in stratosphere, prominently observed in antartica. While this is not a literal hole during spring months this area experiences a dramatic drop in ozone concentrations which allow more harmful Uv to reach the Earth

Question 22

True or false : both the Artic and Antarctic regions have ozone holes, but the one in the Antarctic is mor pronounced.

Answer 22

True

Question 23

The Montreal protocol.

Answer 23

The is was an agreement signed 1986 by 46 countries that set out to reduce Ozone depletion .

They set legally binding targets:
50% reduction in the production and consumption of CFC’s by 1999, using 1986 levels as the baseline.
Froze the emissions of halon and other potent ODS groups at the 1986 emission level.
Controlled 96 chemicals

Question 24

What ensures the success of the Montreal protocols ?

Answer 24

1. There was a lot of scientific evidence as the ozone hole had been recently discovered and scientists had put together compelling reports to move international agreements.
2. There was a robust and binding legal framework which ensured the commitment of all participating countries .this was also combined with the common but differentiated principle where developed countries helped developing countries actively phase out ODSs
3. There were several alternatives to ODSs which made transition easier and without economic disruption.
4. Flexible and adaptive management allowing adjustments and amendments to be made as scientific understanding of ozone enveloped .

Question 25

True or false : the protocols had a slightly delayed timeline for ODS s in developing countries .

Answer 25

True

Question 26

What happens when CFCs are banned ?

Answer 26

They are replaced by HCFCS and those are replaced by HFCs which are much better for the ozone but HFC is still a very forceful greenhouse gas

Question 27

True or false : annual global ozone levels are expected to return to 1980 levels by 2040

Answer 27

True

Question 28

True or false : Artic springtime ozone levels said to return to normal (1980)at 2060

Answer 28

True

Question 29

What are some of the challenges in the work against ODS?

Answer 29

Illegal production and trade of these chemicals still occur .
Not all the important chemicals were covered in treaties.
Persistence of already existing ODS banks in the atmosphere and in some products and equipments.
Increasing demand : developing countries have increased demand for cooling systems and some of these are still dependent on HFCs and or ODSs

Question 30

What has been a major culprit in ozone depletion after the initial ODSs were regulated ?

Answer 30

Nitrous Oxide (N2O)