Atmosphere - Physics Flashcards
What are the functions of the atmosphere?
A protective blanket from solar radiation
A source of CO2 and nitrogen
An intermediate fro the hydrologic cycle
What light does atmosphere absorb?
300-2500nm and radio waves between 0 and 40nm.
What does the self-purificaiton mechanism of the atmosphere allow for?
Chemical conversion of contaminants to non-polluntants like H20
Dry deposition of gas particles
Wet deposition of water soluble contaminants
Barometric Formula
Modles the pressure of air changes with altitude
Pressure
Describes the force associated with transfer of momentum between molecules by collisions
Gas Constant
Pressure time gas volume divided by number of moles and temperature of the gas, relating energy to temperature scale.
Scale Height
The vertical distance by which density and pressure fall by a factor of e^-1
Why does temperature decrease with increasing altitude?
Expansion of empty space thus less kinetic energy
Adiabatic Lapse Rate
The rate at which air temperature changes in response to compression/expansion with altitude.
Adiabatic
Means no heat exchange occuring between an air parcel and its surroundings.
Why does adiabatic lapse rate not apply to water vapour?
Water vapour condenses into liquid as air mass rises
Why does water vapour condensation lower lapse rate?
Release of heat of vaporization and cooling.
What are the layers of the atmosphere?
Troposphere
Stratosphere
Mesosphere
Thermosphere
What does the tropopause do?
Prevents water loss from earth as water condenses into ice ballast
Why does temperature increase with altitude in the stratosphere?
Presence of ozone absorbing UV
What are the ways vertical motion can occur?
Obstruction of objects
High/low pressure systems
Local instability
How are pressure systems created?
Rising of warm air, creates low pressure surfaces, whilst cool air descenion, creates high pressure surfaces.
Lapse Rate
Describes decreasing temperature with height, or depth in the ocean.
Why is moist adiabatic lapse rate lower than dry?
As water vapor rises, it condenses and heat is released.
Dew Point
The temperature which air must be cooled to become saturated with water vapour
How does incident radiation relate to Hadley circulation?
Forces air rising to 15km, with poleward transport.
Why do poleward moving airs increase in speed?
The Law of Conservation of Angular Momentum
Law of Conservation of Angular Momentum
This states that so long as no external torque is applied to the system, angular momentum is conserved
What is an example of angular momentum?
Skater spinning with arms outstretched, a rotational inertia and an inital angular velocity exists; when arms are moved closer, inertia descreases, thus so does angular velocity, increasing speed.
What is angular momentum the product of?
Moment of inertia and angular velocity
Moment of Inertia
Tendency to resist angular acceleration, being the sum of products mass, with the square of its distance from the axis of rotation.
Angular Velocity
Is the rate of change of angular position of a rotating body.
How does angular momentum relate ot Hadley cell poleward movement?
As it moves poleward, it gets closer to Earaths spin axis, decreasing in axis of rotation, with moment of inertia decreasing
Subsidence
The downward motion of an air parcel, increasing in density.
What is hadley cell descent called?
Subsidence.
What does Hadley cell subsidence form?
Subtropic ridge.
Subtropic ridge
A high pressure region encircling the globe, with low precipitation and high evaporation rates.
At subsidence Hadley cells at 30 degreees, how are subtropical highs formed?
Piling up of air, inhibiting formation of clouds, which is why large deserts are found.
Ferrel Cells
These form when decreasing hadley winds deflect poleward, creating westerlies winds.
Rossby Number
Measures systems strongly affected by coriolis force.
What happens in ferrel cells?
Warm surface air pulled poleward, air from poles meeting this wind at 60 degrees N and S, with rising tropic air.
What does 60 degree uplift cause?
Lower pressure surfaces, and unstable watehr conditions.
Fouriers Law
This states that rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area
What is the fouriers law equation?
q =-kDeltaT (q is vector of local heat flux, k the materials conductivity, and DeltaT temperature gradient)
Thermal Conductivity
Describes the rate at which heat is transferred by conduction through a unit cross-section area of a material, DeltaT exists perpendicular to the area.
What is the basis of wind formatioin?
Differences in pressure meaning differences in temperature.
What is required to melt a solid?
Energy to seperate cohesive bonds of the molecules
Latent Heat of Fusion
Describes the energy supplied to a solid required to trigger a change in its physical state to convert it to a liquid
Latent Heat of Vaporization
Energy supplied to a liquid to change to a gas
What happens with heat release in the atmosphere?
Surrounding air is warmed, causing rising and condensation.
