Difference between revisions of "Dry static energy"

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<div class="definition"><div class="short_definition">(<br/>''Also called'' the Montgomery streamfunction.) A [[thermodynamic variable]] similar  to [[potential temperature]], except that the concept of [[static energy]] assumes that any [[kinetic  energy]] is locally dissipated into [[heat]].</div><br/> <div class="paragraph">The amount of this dissipative heating is often negligible. When dry static energy, s, is expressed  in units of kJ kg<sup>&minus;1</sup>, the resulting values are of order 300 kJ kg<sup>&minus;1</sup>, which reinforces the analogy with  potential temperatures in units of Kelvin. Dry static energy is conserved during unsaturated vertical  and horizontal motion, and is defined as  <div class="display-formula"><blockquote>[[File:ams2001glos-De51.gif|link=|center|ams2001glos-De51]]</blockquote></div> where ''c''<sub>''p''</sub> is the [[specific heat capacity]] of air at constant [[pressure]], ''T'' is [[absolute]] temperature, ''g''  is gravitational [[acceleration]], and ''z'' is height. The reference height can be arbitrary; it is sometimes  taken as ''z'' = 0 at ''P'' = 100 kPa to be consistent with potential temperature, or it can be defined  relative to the local ground or [[sea level]]. <br/>''Compare'' [[moist static energy]], [[liquid water static energy]],  [[saturation static energy]].</div><br/> </div>
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<div class="definition"><div class="short_definition">(''Also called'' the Montgomery streamfunction.) A [[thermodynamic variable]] similar  to [[potential temperature]], except that the concept of [[static energy]] assumes that any [[kinetic energy|kinetic  energy]] is locally dissipated into [[heat]].</div><br/> <div class="paragraph">The amount of this dissipative heating is often negligible. When dry static energy, s, is expressed  in units of kJ kg<sup>-1</sup>, the resulting values are of order 300 kJ kg<sup>-1</sup>, which reinforces the analogy with  potential temperatures in units of Kelvin. Dry static energy is conserved during unsaturated vertical  and horizontal motion, and is defined as  <div class="display-formula"><blockquote>[[File:ams2001glos-De51.gif|link=|center|ams2001glos-De51]]</blockquote></div> where ''c''<sub>''p''</sub> is the [[specific heat capacity]] of air at constant [[pressure]], ''T'' is [[absolute]] temperature, ''g''  is gravitational [[acceleration]], and ''z'' is height. The reference height can be arbitrary; it is sometimes  taken as ''z'' = 0 at ''P'' = 100 kPa to be consistent with potential temperature, or it can be defined  relative to the local ground or [[sea level]]. <br/>''Compare'' [[moist static energy]], [[liquid water static energy]],  [[saturation static energy]].</div><br/> </div>
 
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Latest revision as of 16:50, 25 April 2012



dry static energy

(Also called the Montgomery streamfunction.) A thermodynamic variable similar to potential temperature, except that the concept of static energy assumes that any kinetic energy is locally dissipated into heat.

The amount of this dissipative heating is often negligible. When dry static energy, s, is expressed in units of kJ kg-1, the resulting values are of order 300 kJ kg-1, which reinforces the analogy with potential temperatures in units of Kelvin. Dry static energy is conserved during unsaturated vertical and horizontal motion, and is defined as
ams2001glos-De51
where cp is the specific heat capacity of air at constant pressure, T is absolute temperature, g is gravitational acceleration, and z is height. The reference height can be arbitrary; it is sometimes taken as z = 0 at P = 100 kPa to be consistent with potential temperature, or it can be defined relative to the local ground or sea level.
Compare moist static energy, liquid water static energy, saturation static energy.


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