Blood Moon, semi permanent hair dye red - 118 ml - Lunar Tides

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integer so that positive values for σ {\displaystyle \sigma } correspond to eastward propagating tides Migrating tides are Sun synchronous – from the point of view of a stationary observer on the ground they propagate westwards with the apparent motion of the Sun. As the migrating tides stay fixed relative to the Sun a pattern of excitation is formed that is also fixed relative to the Sun. Changes in the tide observed from a stationary viewpoint on the Earth's surface are caused by the rotation of the Earth with respect to this fixed pattern. Seasonal variations of the tides also occur as the Earth tilts relative to the Sun and so relative to the pattern of excitation. [1] Following this growth with height atmospheric tides have much larger amplitudes in the middle and upper atmosphere than they do at ground level. The primary source for the 24-hr tide is in the lower atmosphere where surface effects are important. This is reflected in a relatively large non-migrating component seen in longitudinal differences in tidal amplitudes. Largest amplitudes have been observed over South America, Africa and Australia. [3] Lunar atmospheric tides [ edit ] Non-migrating tides can be thought of as global-scale waves with the same periods as the migrating tides. However, non-migrating tides do not follow the apparent motion of the Sun. Either they do not propagate horizontally, they propagate eastwards or they propagate westwards at a different speed to the Sun. These non-migrating tides may be generated by differences in topography with longitude, land-sea contrast, and surface interactions. An important source is latent heat release due to deep convection in the tropics.

The fundamental solar diurnal tidal mode which optimally matches the solar heat input configuration and thus is most strongly excited is the Hough mode (1, −2) (Figure 3). It depends on local time and travels westward with the Sun. It is an external mode of class 2 and has the eigenvalue of ε 1 For a fixed longitude λ {\displaystyle \lambda } , this in turn always results in downward phase progression as time progresses, independent of the propagation direction. This is an important result for the interpretation of observations: downward phase progression in time means an upward propagation of energy and therefore a tidal forcing lower in the atmosphere. Amplitude increases with height ∝ e z / 2 H {\displaystyle \propto e General solution of Laplace's equation [ edit ] Figure 2. Eigenvalue ε of wave modes of zonal wave number s = 1 vs. normalized frequency ν = ω/Ω where Ω = 7.27 ×10 −5s −1 is the angular frequency of one solar day. Waves with positive (negative) frequencies propagate to the east (west). The horizontal dashed line is at ε c ≃ 11 and indicates the transition from internal to external waves. Meaning of the symbols: 'RH' Rossby-Haurwitz waves ( ε = 0); 'Y' Yanai waves; 'K' Kelvin waves; 'R' Rossby waves; 'DT' Diurnal tides ( ν = −1); 'NM' Normal modes ( ε ≃ ε c) Solar energy is absorbed throughout the atmosphere some of the most significant in this context are [ clarification needed] water vapor at about 0–15km in the troposphere, ozone at about 30–60km in the stratosphere and molecular oxygen and molecular nitrogen at about 120–170km) in the thermosphere. Variations in the global distribution and density of these species result in changes in the amplitude of the solar tides. The tides are also affected by the environment through which they travel.

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Atmospheric tides are also produced through the gravitational effects of the Moon. [4] Lunar (gravitational) tides are much weaker than solar thermal tides and are generated by the motion of the Earth's oceans (caused by the Moon) and to a lesser extent the effect of the Moon's gravitational attraction on the atmosphere. The set of equations can be solved for atmospheric tides, i.e., longitudinally propagating waves of zonal wavenumber The reason for this dramatic growth in amplitude from tiny fluctuations near the ground to oscillations that dominate the motion of the mesosphere lies in the fact that the density of the atmosphere decreases with increasing height. As tides or waves propagate upwards, they move into regions of lower and lower density. If the tide or wave is not dissipating, then its kinetic energy density must be conserved. Since the density is decreasing, the amplitude of the tide or wave increases correspondingly so that energy is conserved.

Hence, atmospheric tides are eigenoscillations ( eigenmodes)of Earth's atmosphere with eigenfunctions Θ n {\displaystyle \Theta _{n}} , called Hough functions, and eigenvalues ε n {\displaystyle \varepsilon _{n}} . The latter define the equivalent depth h n {\displaystyle h_{n}} which couples the latitudinal structure of the tides with their vertical structure. Migrating solar tides [ edit ] Figure 1. Tidal temperature and wind perturbations at 100 km altitude for September 2005 as a function of universal time. The animation is based upon observations from the SABER and TIDI instruments on board the TIMED satellite. It shows the superposition of the most important diurnal and semidiurnal tidal components (migrating and nonmigrating). a cos ⁡ φ ( ∂ u ′ ∂ λ + ∂ ∂ φ ( v ′ cos ⁡ φ ) ) + 1 ϱ o ∂ ∂ z ( ϱ o w ′ ) = 0 {\displaystyle {\frac {1}{a\,\cos \varphi }}\,\left({\frac {\partial u'}{\partial \lambda }}\,+\,{\frac {\partial }{\partial \varphi }}(v'\,\cos \varphi )\right)\,+\,{\frac {1}{\varrho _{o}}}\,{\frac {\partial }{\partial z}}(\varrho _{o}w')=0}At ground level, atmospheric tides can be detected as regular but small oscillations in surface pressure with periods of 24 and 12 hours. However, at greater heights, the amplitudes of the tides can become very large. In the mesosphere (heights of about 50–100km (30–60mi; 200,000–300,000ft)) atmospheric tides can reach amplitudes of more than 50m/s and are often the most significant part of the motion of the atmosphere. Atmospheric tides are global-scale periodic oscillations of the atmosphere. In many ways they are analogous to ocean tides. Atmospheric tides can be excited by: