the ability or capacity to do work on matter - for example, to move an air parcel or raise the temperature of an air parcel
measured in
joules (J), where one J = N$\times$m ( N=newton and m=meter) = kg $\times$ m/sec$^2$ $\times$ m = kg $\times$ m$^2$/sec$^2$.
A newton (N) is the force equivalent to accelerating a one kilogram mass one meter per second per second (kg$\cdot$ m/sec $\cdot$ 1/sec)
calories (cal), where one cal is equivalent to the energy required to raise one gram of water one degree C at standard atmospheric pressure (1013 mb) and initial temperature of 3.98 C. This amount of energy is referred to as a small calorie. One cal is equivalent to 4.186 J.
A large calorie (C), or kilogram calorie, approximates the energy needed to increase the temperature of 1 kg of water by 1 degree C. This is about 4.186 kilojoules (kJ), and exactly 1000 small calories. (Note: The kilogram calorie is what is meant by a "food calorie.")
Energy Types (important to meteorology)
potential energy (PE)
PE = $m \cdot g \cdot z$, where $m$ is the mass (in kg), $g$ is the acceleration due to gravity (= 9.8 m/$\mbox{sec}^2$), and $z$ is the elevation (in meters). The resultant energy has units of Joules (J)
kinetic energy (KE)
KE = $\frac{1}{2}m \cdot v^2$, where $m$ is the mass (in kg) and $v$ is the velocity of the parcel (in m/sec). The resultant energy has units of Joules (J).
The thermal energy (on the molecular or atomic scale) is the portion of a parcel's internal energy that results in the parcel's temperature, and has a kinetic component and a potential component.
The potential portion of thermal energy includes aspects of atomic vibrations.
The temperature $T$ of the parcel is a measure of the average kinetic energy due to translation of the individual atoms and molecules that make up the parcel.
$T = \alpha \cdot m_w \cdot \bar{v}^2$
where $m_w$ is the (average) molecular mass of the parcel, $\bar{v}$ is the average speed of the molecules, and the constant $\alpha$ = $4.0 \times 10^{-5}$ $\mbox{K} \mbox{m}^2 / \mbox{sec}^2$
The First Law of Thermodynamics is used to derive a relationship between the change in energy $\Delta Q$ of a system or object and the change in temperature $\Delta T$:
$\Delta Q = C\cdot m \cdot \Delta T$
where $m$ = mass and $C$ = specific heat (or heat capacity) of the
thin gasses are selective absorbers - only radiation at certain wavelengths is absorbed.
radiation is re-emitted at the same wavelength (Kirchoff's Law)
Equivalent temperature : $T_e = T + \frac{L}{C_p}W$, where $T$ = parcel temperature, $L$ is the latent heat of the phase change, $C_p$ is the heat capacity of dry air (0.24 cal/gm), and $W$ is the mixing ratio in gm/gm or kg/kg. A simple derivation of this result is given here.