Lecture Two and Three

Weather

Condition of the atmosphere at a particular location and moment

What are some atmospheric conditions of weather?

Temperature, humidity, pressure, wind speed and direction, cloud cover, and precipitation

What causes weather?

The effect of the Sun on the Earth

What is climate?

Region in the condition of the atmosphere over many years

What is climate described by?

Long term averages of atmospheric conditions such as temperature and precipitationW

What is the study of climate?

Climatology or climate science

What is the study changes of climate in the past and for the future?

Climatologists or climate scientists

What is meteorology?

Study of weather variables, processes that cause weather, interaction of the atmosphere with the Earth’s surface and ocean

What is the difference between meteorologist and atmospheric scientist?

Meterologist: Those forecasting the weather

Atmospheric scientist: Someone who boadly studies weather, climate, or atmospheric chemistry

What is the atmosphere?

Fluid, thin layer surrounding the Earth, a mixture of invisible gas with solid and liquid particles that stay in place on account of the gravitational forces

What is the Earth’s diameter and atmosphere?

Diameter: 8000 miles

Atmosphere: 100 miles

Describe the evolution of the Earth’s atmosphere

4.5 billion years ago: hydrogen, helium

Volcanic eruptions: Water vapor, carbon dioxide, nitrogen

Earth’s cooling to clouds to surface water

CO2 dissolved and accumulated in oceans

Bacteria in water then vegetation, which produces oxygen (photosynthesis)

Nitrogen chemically stable and accumulated in the atmosphere

What is vital to meterology and climatology?

Variable gases

How can we understand atmospheric concentrations of trace gases?

Sources and sinks need to be investigated

What percent of oxygen, sources, sinks

20.95%

Sources: photosynthesis, ocean phytoplankton

Sinks: decay of organic matter, oxidation, combustion, respiration

What percent of nitrogen, sources, sinks

78.08%

Sources (denitrification): Decaying plant and animal

matter

Sinks (“nitrogen fixation”):

• Soil bacteria

• Ocean phytoplankton

• Lightning – hot enough to break

N2 and form nitrous oxides (NOx)

Water Vapor (0-4%)

Greenhouse gas!

Sources:

• Evaporation (liquid to vapor)

• Sublimation (ice to vapor)

• Transpiration

Sinks:

• Condensation (vapor to liquid)

• Deposition (vapor to ice)

• Precipitation

Carbon Dioxide

Greenhouse gas!

Sources:

• Biomass decay - Deforestation

• Respiration - Volcanic eruptions

• Combustion

Sinks:

• Photosynthesis

• Ocean phytoplankton

• Dissolved directly into ocean surface

Methane (1.9 ppm)

Greenhouse gas!

Sources:

• Anaerobic environments

Wetlands, rice paddies

Cows and other livestock animals

Termites

• Biomass burning

Sinks:

• Interaction with OH in atmosphere

Nitrous Oxide (N2O)

Greenhouse gas!

Sources:

• Bacteria in soils/oceans

• Combustion (cars, biomass)

• Fertilizers

Sinks:

• Stratospheric photochemistry

Ozone (O3)

O3 layer forms in the stratosphere 600 million years ago (required sufficient O2)

UV light is harmful to organisms and formation of stratospheric O2 allowed life to move from the oceans where they are protected from UV light, to land

Photosynthesis becomes largest source of O2

O2 levels stabilize at 20% from balance between photosynthetic O2 production and removal through respiration and decay of organic material

What did the Chapman Mechanism propose?

Ozone layer originates from the photolysis of atmospheric O2

1. O2 + light (240 nm) O + O

   2. O2 + O  O3

   3. O3 + UV  O2 + O

• R3 is not a terminal sink for O3 since the O atom product may recombine with O2 by R2 to regenerate O3

What is the result of the Chapman Mechanism?

Reproduces the shape of the O3 through the stratosphere but overestimates the observed O3 mixing ratio by a factor of two or more thus the source is too big or the sink is too small

What is well constrained with spectroscopic data?

R1, so we know the source. Therefore, there must be additional sinks

Stratosphere

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Troposphere

Troposphere O3: photochemical smog

What are the three stratospheric O3 sinks?

1. Hydrogen oxide radical

2. Nitrogen oxide radicals

3. Chlorine oxide radicals

What is an atmospheric sink?

Natural/chemical process that removes greenhouse gas + pollutant from the atmosphere

What is an important characteristic of sink 3?

Highly catalytic, actively destroying ozone, not particularly fast

What do CFC’s stand for?

Chloroflurocarbons

What are greenhouse gasees

Artificial, chemically inert, nontoxic, deplete ozone in the stratosphere

What is an ozone hole

Rapid depletion of stratosphere ozone layer with presences of CFC’s, cold temperature, and sunlight

What is an example of this?

Polar stratospheric clouds form which encourages fast O3 depletion through photolysis

What are sources of chloroflurocarbons?

Propellants in aerosol cans, refrigerants, blowing of plastic foam insulation, cleaning for electronics

What is the issue with CFC’s?

Can upset balance between ozone production and destruction

INTRODUCTION TO WEATHER MAPS

Continue to the next section

What is the Coordinated Universal Time?

The reference clock adopted by weather organizations around the world

What is a front?

Boundaries between air masses

Define isotherms

Connect observations of the same temperature

Define isobars

Connect observations of the same pressure

What is a station model

Model that is used with data from specific locations coded

What is this?

Cold front

What is this?

Warm front

What is this?

Stationary front

What is this?

Occluded front

How to describe the direction of movement for each of the fronts?

Cold: Dense cold air mass advances and replaces warmer air mass

Warm: Move slowly as lighter warm air mass advances and glides up over a retreating cold air mass

Occluded: Move forward as a fast moving cold front overtakes a slower warm front

Stationary: Do not move significantly, because cold and warm air masses meet with equal force and stall out. Surface winds blow parallel to the front rather than pushing it forward