Lect 01 Radar

Synoptic in context refers to horizontal dimensions and length of time of atmospheric phenomena ; such as Extra-tropical cyclones and Anti-cyclones, Troughs and Ridges and extent to Frontal zones and Jets.

Classification of atmospheric phenomena The atmospheric phenomena classified by two factors, their horizontal dimensions and time scales. Time scale means; the time it takes air to travel completely across the feature. For example; an intense extra-tropical cyclone may form over a 1-2 day period, not in 3 hours, 10 minutes or a month.

There are several common classification schemes for phenomena: Isidoro Orlanski sub-divides phenomena according to the order of magnitude of the horizontal extent of each phenomena, using Greek letters and the prefixes ; “micro”, “ meso “, and “ macro “

Ted Fujita sub-divides phenomena according to the order of magnitude of the horizontal extent of each phenomena relative to the circumference of the earth at the equator.

In general, meteorological features occur over a wide range of space and time scales. It is interesting that phenomena having long space scales have long time scales, and vies versa, with ration between horizontal space and time scale is roughly of the same order of magnitude for all features ( i,.e. 10 ms -1 )

The role of observations and theory Can we could classified phenomena in terms of physical characteristics? We have two ways for detect weather phenomena, by synoptic or dynamic meteorology.

Synoptic Meteorology is largely based upon observations. on the other hand ; Dynamic meteorology is based on the acceptance of physical laws and deductions about atmospheric behavior based upon those laws.

We can first observe a phenomenon and describe its characteristics, then analyze it to learn why it forms and why it behaves as it does, and ultimately to predict its behavior.

Or we can predict its existence based upon physical law. and then search for it in nature

For example, the extratropical cyclone was first observed, then analyzed, and much later numerically predicted. On other hand, Gravity waves were first discussed as solotions to a set of dynamical equations, and later were sought observationally.