( ( ( ( Air masses ) , ) ( their ( ( nature and ) properties ) ) ) ; )
(ROOT (NP (NP (NNP Air) (NNS masses)) (, ,) (NP (PRP$ their) (NN nature) (CC and) (NNS properties)) (: ;)))
Air masses, their nature and properties;
(ROOT (S (NP (NP (CD One)) (PP (IN of) (NP (NP (DT the) (NNS properties)) (PP (IN of) (NP (DT an) (NN air) (NN mass)))))) (VP (VBZ is) (SBAR (IN that) (S (NP (DT an) (NN air) (NN mass)) (VP (VBZ has) (NP (NP (JJ similar) (NN temperature) (CC and) (NN moisture) (NNS properties)) (PP (IN throughout) (NP (PRP it)))))))) (. .)))
One of the properties of an air mass is that an air mass has similar temperature and moisture properties throughout it.