Marking
...and a small interlude with a phone call from BAS asking about upward flowing electrons.
Three mechanisms:
Scattering - electrons are just particles bouncing around. They occasionally bounce back, indeed plenty do, though this creates a small upward flux far lower than the downward flux (and increasingly comparitively smaller the higher the energy of the forward flux).
Charge reallignment - this affects any ionising thing that enters the atmosphere. Ionisation leads to most the momentum going to the small electron seperating from the big particle, leaving a static positive layer in the position of greatest ionisation and a layer where the electrons (those that don't themselves then head up) end up. Background electrons then move away from the negative layer towards the positive layer to neutralise this.
Birkland currents - dumping massive amounts of negative charge into the ionosphere leads to a negatively charged ionosphere (I know, I was as surprised as you are...), which cannot be. This is negated by a current of opposite polarity completing the circuit between the ionosphere and the magnetosphere. This takes the form of either protons flowing in or electrons flowing out, or a combination of the two.
There you are.
Also did some marking
...as well as some preparation for taking people on a tour of Mill Hill tomorrow. Scary. For them, not me...
Three mechanisms:
Scattering - electrons are just particles bouncing around. They occasionally bounce back, indeed plenty do, though this creates a small upward flux far lower than the downward flux (and increasingly comparitively smaller the higher the energy of the forward flux).
Charge reallignment - this affects any ionising thing that enters the atmosphere. Ionisation leads to most the momentum going to the small electron seperating from the big particle, leaving a static positive layer in the position of greatest ionisation and a layer where the electrons (those that don't themselves then head up) end up. Background electrons then move away from the negative layer towards the positive layer to neutralise this.
Birkland currents - dumping massive amounts of negative charge into the ionosphere leads to a negatively charged ionosphere (I know, I was as surprised as you are...), which cannot be. This is negated by a current of opposite polarity completing the circuit between the ionosphere and the magnetosphere. This takes the form of either protons flowing in or electrons flowing out, or a combination of the two.
There you are.
Also did some marking
...as well as some preparation for taking people on a tour of Mill Hill tomorrow. Scary. For them, not me...
Labels: Marking, Mill Hill, Precipitation
