Solar - Astronomical Theory Flashcards
Astronomical Theory
This argues that long-term variations of earths orbital parameters are the cause of the ice age successiions during geological periods.
Maunder Minimunm
A period between 1650 to 1715, associated with extremely low solar activity.
What is believed to have caused the Maunder Minimum?
Very few sunspots on the sun surface, with decreased sun brightness
Why do sunspots increase brightness?
UV radiation increases dramatically during high sunspot activity.
Solar Cycle
An 11 year cycle of solar activity, characterised by a rise and fall in numbers and surface area of sunspots.
Sunspots
Dark areas on the surface of the sun, being cooler than other parts,.
What do more sunspots mean for atmosphere?
More energy and icnreasing temperatures.
Why do sunspots increase brightness?
Increased darkness of sunspots mean surrounding faculae results in net increase of irradiance.
Facula
Bright photosphere spots formed from concentrated magnetic field lines
Where do facula often form?
Around sunspots being hotter and brighter than photosphere.
Solar Flares
Explosions of energy due to magnetic field crossing/tangling NEAR sunspots.
What are solar cycles associated with?
Extrem UV and Sun X-ray emissions, affecting Earths upper atmosphere.
What characterises Solar Cycles?
Dynamo theory
Dynamo Theory
A mechanism of which celstial bodies generate magnetic fields.
What is dynamo theory dependent on?
An electrically conductive field medium
Kinetic energy by planetary motion
Internal energy soruce driving convective motions within the fluid
Convection
The transfer of heat by fluid movement between areas of temperature.
What does the interior of the sun consist of?
Ionised plasma and Magnetic fields.
What does the movement of Ionised plamsa and Magnetic fields do?
Set up currents
Plasma
Where gas has enough energy supplied to provide free electrons from atoms or molecules, allowing both species, ions and electrons, to coexist
What causes the suns magnetic field?
Plasma flow churned by enormous heat by nuclear fusion
Why are sunspots cooler/darker than their surroundings?
The magnetic field is so trong that convective flow is cut off.
Shearing Forces
Unaligned forces pushing one part of a body in a specific direction, and another part of the body in the opposite direction.
What two effects dictate dynamo?
The Omega and Alpha effects
The Omega Effect
The rotation rate change as a function of lattitude and radius
The Alpha Effect
Increased nucleophilicity of an atom due to presence of adjacent atoms with lone pair electrons.
How do solar cycles most affect earths climate?
Total solar irradiance.
Total Solar Irradiance
The integrated energy input to the top of earths atmosphere at a base mean distance from the sun.
Thermal Inertia
The property of a material that expresses the degree of slowness with with its temperature reaches that of the envrionment
Solar Convective Zone
The outer most layer of the solar interior.
What is low solar forcing proportional to?
Thermal inertic of solar convective zone
Milankovitch Cycles
Describes the various astronomical forcings that influence earths climate.
What does earths eccentricit vary between?
22,1 to 24.5 derees.
