# Presentation: 343158

## Advancement Training

**System of Measurement  (Unit 1-Lesson 1)**

**Operations Department Training**

## System of MeasurementIntroduction

- To work in the field of meteorology, you must have a basic understanding of the science of measurement (metrology).
- The Metric System (CGS, centimeter-gram-second) has been recognized for use in science and research.
- The metric system is easy to learn as it is based on decimals.
- CGS describes physical events, with units that measure length, weight, and time, respectively. The derivation of those units are included in this brief.

## System of MeasurementLearning Objective

- Recognize the units of measure used in the Metric System and how this system of measurement is used in Meteorology.

## System of MeasurementLength

- The meter is slightly larger than the English yard (39.36 inches vs 36 inches).
- Prefixes are used in conjunction with the meter to denote smaller or larger units of the meter.

## System of MeasurementCommon Prefixes

- _Prefix_ (1)_	__Symbol_	_Decimal Value_	_Sci Notation_
- Kilo		    K			1000			 103
- Hecto	    	    H		            100		           102
- Deka		    D			    10			 101
- Deci		    d			     .1			 10-1
- Centi		    c			   .01			 10-2
- Milli		    m		            .001			 10-3
- (1)  These prefixes are used with all metric units such as meters, grams, liters, and seconds (eg., kilometers, hectometers, centiliters, milliseconds).

## System of MeasurementArea 

- A square has four equal sides and it is a one-plane figure-like a sheet of paper.
- To determine how much surface area is enclosed within the square you multiply the length of one side by the length of the other equal side (LxL).
- Ex. If the sides were 1 cm in length the area of the square would be 1cm x 1cm = 1 square cm or 1 cm2

## If squares having an area of 1 cm2 were stacked on top of each other until the stack was 1 cm tall, you would end up with a cube whose sides were each 1 cm in length.
To determine volume of the cube you simply multiply the length by the width and height (V=LWH).
Each side is 1 cm you end up with a volume of 1 cubic centimeter (cm3).
Once determining volume is understood, you are ready to learn about weight.

- To determine volume of the cube you simply multiply the length by the width and height (V=LWH).
- Each side is 1 cm you end up with a volume of 1 cubic centimeter (cm3).
- Once determining volume is understood, you are ready to learn about weight.

*System of Measurement**Volume*

## System of MeasurementWeight

- The conventional unit of weight is the gram (gm).  You could use the previous slides table and substitute gram for meter and the symbol (gm) for the symbol (M).
**The gram is the weight of 1 cm**3** of pure water at 4 degrees C. *
**The weight of the 1 cm**3** of water is 1 gm.*
**Weight and mass are proportional to each other.*
- However, the weight of the 1cm3 of water changes moving away from the gravitational center of the Earth.  In space the water is weightless, but it is still a mass.
- Mass is expressed as a function of inertia/acceleration, while weight is a function of gravitational force.  When we express the movement of an object we use the terms mass and acceleration.

## System of MeasurementDensity

- With the previous explanation of grams and centimeters, you now understand how physical factors can be measured and described.
- For example, density is the weight something has per unit of volume.  The density of water is given as 1 gram per cubic centimeter or 1gm/cm3.

## System of MeasurementForce

- *Force is measured in dynes.
- A dyne is the force that moves a mass of 1 gram, 1 centimeter per square second.