Animations Most of these are in the Quicktime .mov format although a few are animated GIF files. Quicktime should be able to play all of them. 2.2 Linpol.mov This animation can be run as a continuous loop. It represents linearly-polarised radiation propagating to the right. The electric field (red) oscillates in the vertical plane and the magnetic field (blue) oscillates in the horizontal plane. 2.2 This animation can be run as a loop. It represents left-hand circularly polarised (LHC) radiation propagating to the right. The electric field is shown as red lines and the magnetic field as blue lines. 3.1.1 Attenwave.mov This animation can be run as a continuous loop. It represents an exponentially decaying wave propagating to the right. 3.1.3 Dispersion.mov This animation shows a modulated wave travelling to the right in a dispersive medium. The group velocity (speed with which the modulating envelope travels) is greater than the phase velocity (speed of the carrier wave). In this example the modulating function does not become elongated as the pulse propagates. 3.2 Snell0.mov, Snell30.mov, Snell60.mov These three animations are best viewed simultaneously and as continuous loops. They show electromagnetic waves being refracted into a medium with higher refractive index at different angles of incidence. The colours represent different phases of the wave motion. 3.4.1 Atom1.mov, Atom2.mov, Atom3.mov These three animations are best viewed simultaneously and as continuous loops. They represent the ground state and first two excited states of the hydrogen atom. The large sphere represents the nucleus (proton) and the small sphere the electron. The animations are not to scale, but show that at higher (less negative) energy levels the electron is further from the nucleus and has less kinetic energy. 3.4.1 Vibration1.mov. Vibration3.mov, Vibration5.mov These three animations are best viewed simultaneously and as continuous loops. They represent the ground state and first two excited vibrational states of a diatomic molecule such as carbon monoxide. The frequencies (and hence energies) of these states are in the ratio 1:3:5. 3.4.1 RotateJ1.mov, RotateJ2.mov These two animations are best viewed simultaneously and as continuous loops. They represent the first two excited rotational states of a diatomic molecule such as carbon monoxide, with quantum numbers J=1 and J=2 respectively. 6.1.2 Scanners.mov This animation is best viewed as a continuous loop. The top part represents step-stare imaging using a two-dimensional sensor. The middle part shows line-scanning with a one-dimensional sensor (pushbroom scanning). The bottom part shows whiskbroom scanning. 6.1.2 Spinscan.mov This animation is best viewed as a continuous loop. It represents spin-scanning of the Earth's disc by a sensor on a geostationary satellite. 7.1.3 conescan.mov This animation illustrates the principle of conical scanning by a passive microwave radiometer. 8.2.1 RAflat.mov This animation illustrates how the scattering zone from a radar altimeter intersects the flat Earth. The left side of the animation shows a side view and the right side shows a plan view. The scattering area begins as a growing disc, then becomes an annulus. 8.2.4 RArough.mov This animation illustrates how the scattering zone from a radar altimeter intersects a rough surface. The left side of the animation shows a side view and the right side shows a plan view. Compare 8.2.1 Raflat.mov 10.3 Elliptical.mov This animation is best viewed as a continuous loop. It shows how a satellite (small circle) moves in an elliptical orbit around the Earth (larger circle). 10.3.1 Precess1.mov Precession of a satellite's orbit around the Earth's polar axis, viewed from a fixed point in space and looking down on the North Pole. The rate of precession has been greatly exaggerated. 10.3.1 Precess2.mov Precession of a satellite's orbit in its own plane, viewed perpendicularly to the plane of the orbit. The rate of precession has been greatly exaggerated. 10.3.2.1 Geostationary.gif Motion of a satellite in a geostationary orbit seen from a fixed point in space. The blue circle is centred on the satellite and the red circle shows the subsatellite point on the Earth's surface. 10.3.2.2 Molniya.gif Motion of a satellite in a Molniya orbit seen from a fixed point in space. The blue circle is centred on the satellite and the red circle shows the subsatellite point on the Earth's surface. 10.3.2.2 Molniya3.mov Animation to show how three satellites in the same Molniya orbit can give more or less continuous observation of a fixed point at high latitude. 10.3.2.3 Landsat.gif Motion of a satellite in a low Earth orbit such as is used by the Landsat satellites, as seen from a fixed point in space. The blue circle is centred on the satellite and the red circle shows the subsatellite point on the Earth's surface. 10.3.2.4.1 Landsat1.mov Animation to show a single orbit of the Landsat-7 satellite. Time in orbit is shown in days, local time in hours.