Climatology

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FO 101

FOREST ECOLOGY

CLIMATOLOGY PART

A Compendium

By

Munishi, PKT and Madoffe, S.S.

August 2008

1. INTRODUCTION

Trees and animals survival and growth on given site and represent an integrated response to a complex of many fluctuating and interacting environmental factors. The environmental factors are conveniently grouped into biotic (genetic variation, stand density, competition, pests and diseases) and abiotic factors (climatic conditions, topographic effects and edaphic variables). In addition to the effects on tree survival and growth, some climatic parameters play a significant role in choice of tree species, timing and/or choice of silvicultural and harvesting operations

In this course, a description of meteorological parameters, processes, equipment, data collection, and analysis methods, and the relationship between some climatic variables and trees survival, growth, timing and/or choice of silvicultural and harvesting operations are presented and discussed.

2. DEFINITIONS

Climatology = science that seeks to describe and explain the nature of climate, Why it differs from place to place, and
How it is related to other elements of the natural environment and to human activities. Climatology is closely allied with, but often confused with meteorology They study similar things, but separated by the length of time over which they operate.

Meteorology
The study of the atmosphere and its phenomena as well as the atmosphere’s interaction with the earth’s surface oceans and life in general.

Atmosphere
The envelope of gases that surround a planet and are held to it by the planet’s gravitational attraction. The earth’s atmosphere is mainly Nitrogen and oxygen.

Layers of the atmosphere:
Air pressure and density decrease with height above the earth, rapidly at first, then more slowly. Air temperature has however, more complicated vertical profile. Air temperature normally decreases from the earth’s surface up to an altitude of about 11 km – Temperature lapse. Occasionally, some regions air temperature increases with height = Inversion.

The main atmospheric layers are: The troposphere – Earth’s surface to about 11 km, Sratosphere is above troposphere and below mesosphere between 11km and 50km. Mesosphere, between stratosphere and thermosphere between 50km – 80km above earth’s surface, and Thermosphere above mesosphere above about 85km where temperature increases with height.

Weather
The condition of the atmosphere at any particular time and place. Always changing, sometimes very rapid changes, sunshine clear sky, complete cloud cover, drizzle, storm, etc. In some areas atmospheric conditions may be very stable with little fluctuation. It is also referred to as the day-to-day state of the atmosphere pertaining to short term changes in conditions of heat, moisture, and air circulation.

Weather Elements
Weather is comprised of the following elements
(a) Air temperature
(b) Air pressure
(c) Humidity- measure of water vapour concentration in the atmosphere (d) Clouds and fog
(e) Precipitation
(f) Visibility
(g) Wind

Climate
Climate is a broad generalisation of the weather elements. It is a measure and abbreviation of the weather elements over specified time intervals for many years that gives the average weather or climate of an area/region.

Climate represents therefore the accumulation of daily and seasonal weather events over a long period of time. It also includes the extremes of weather e.g. heat waves of summer and cold spell of winter that occurs ever a particular region. The frequency of extremes help distinguish among climate with similar averages.

“Climate is what you expect … weather is what you get!” Climate is an “envelope of possibilities” within which the weather bounces around Climate is determined by the properties of the Earth system itself (the boundary conditions), whereas weather...
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