  Intermolecular correlations in liquid water at ambient conditions have
generally been characterized through short range density fluctuations described
through the atomic pair distribution functions (PDF). Recent numerical and
experimental results have suggested that such a description of order or
structure in liquid water is incomplete and there exists considerably longer
ranged orientational correlations in water that can be studied through dipolar
correlations. In this study, using large scale classical, atomistic molecular
dynamics (MD) simulations using TIP4P-Ew and TIP3P models of water, we show
that salts such as sodium chloride (NaCl), potassium chloride (KCl), caesium
chloride (CsCl) and magnesium chloride (MgCl$_2$) have a long range effect on
the dipolar correlations, which can not be explained by the notion of structure
making and breaking by dissolved ions. The relative effects of cations on
dipolar correlations are observed to be consistent with the well-known
Hofmeister series. Observed effects are explained through orientational
stratification of water molecules around ions, and their long range coupling to
the global hydrogen bond network by virtue of the sum rule for water. The
observations for single hydrophilic solutes are contrasted with the same for a
single methane (CH$_4$) molecule. We observe that even a single small
hydrophobe can result in enhancement of long range orientational correlations
in liquid water,- contrary to the case of dissolved ions, which have been
observed to have a reducing effect. The observations from this study are
discussed in the context of hydrophobic effect.
