Blair says

Whatisclimate says

Climate is the summary or the resultant of all the manifold weather influences.

What is the result of all weather influences?

And in many cases it is the one natural element of greatest significance in the life of man.

Indeed. The term weather is of little help in scientific research.

Meteorology is closely related to physics;

Meteorology should study weather by physical terms, and explain weather by layman’s expectations.

climatology is intimately connected with geography.

That is what layman associate –inter alias- with climate (which is related to the origin of the term, the Greek word ‘klima’)

There is another aspect, called ‘physical climatology’, which is concerned with the physical processes that produce climate.

Physical processes ‘produce’ weather but neither climate, nor weather statistics.

Whatisclimate notes

The air is subject to varying influences from the sun and the earth, and it moves with great freedom over the earth’s surface. For these reasons its distribution and it’s physical condition are continually changing. The condition and behaviour of the air at a given time and place constitute weather.

A very subjective explanation. Is ‘air’ weather?

In order to describe and record the weather, we need instruments for the accurate measurement of the physical properties of the air. We must measure or observe (1) the temperature of the air, (2) its pressure, (3) the speed and direction of its motion, (4) its moisture content, (5) the state of the sky as to cloudiness or the amount of precipitation since the last observation.

These are the six most important weather elements

What about all the unimportant weather elements?

Meteorology, as the science of the weather, attempts to apply physical principles to an explanation and interpretation of all the varied weather phenomena.

Whatisclimate

For many purposes it is more important to know, not what the weather in Ohio or in Chile is today, but what it usually is. In other word, we must know what the average condition of the atmosphere is –how hot in summer, how cold in winter, how much rain or snow falls in a year, whether the air is moist or dry, and innumerable other questions of this kind.

Blair says it: we want to know the average conditions.

Thus we are often interested in the climate of a place rather than in the weather. The weather of a given moment involves a number of elements, as has been noted, and is difficult to state completely and accurately.

Why does Blair suddenly change from average weather to climate?

Climate, involving the combination and integration of the ceaselessly changing weather conditions, is a much more complex and difficult concept.

This is not an explanation of what climate is.

Climate is the summary or the resultant of all the manifold weather influences.

The summery of weather influences is weather or average weather.

As such, it is one of the most important and influential factors of our environment, and in many cases it is the one natural element of greatest significance in the life of man.

Weather influences the life of man, not statistics

Whatisclimate

A discussion of the phenomena of climate is the province of the science of climatology.

Climatology treats of the component elements of weather and climate, such as temperature and rainfall, of their actual distribution over the earth, and of the factors, which determine and control their distribution. Since climate has so many far-reaching, practical, and direct applications to the activities of man, climatology emphasizes human relations and is largely descriptive in character.

Put instead of Climatology the word Meteorology and ask why is a separation made?

Meteorology is closely related to physics; climatology is intimately connected with geography.

???

These statements apply more particularly to that phase of the subject known as ‘descriptive climatology’.

There is another aspect, called ‘physical climatology’, which is concerned with the physical processes that produce climate.

Not one single physical process produces climate (only weather and one can compile data to ‘average weather’.

Physical climatology attempts to analyse and interpret the observational data in terms of cause and effect, and is akin to physics and meteorology.

Physical climatology can not exist in real.