FULL LECTURE NOTES ON WEATHER AND CLIMATE

Difference between weather and climate




WEATHER

Weather can be defined as the physical condition or state of the atmosphere at a particular time and place.

Most weather happens in the part of the earth’s surface called the troposphere

temperature, pressure, wind, humidity, and precipitation interact with each other.




they influence the atmospheric conditions like the direction and velocity of the wind, amount of insolation, cloud cover, and the amount of precipitation.

Weather can be defined as the physical condition or state of the atmosphere at a particular time and place. Most weather happen the part of the earth's surface called the troposphere

these are known as elements of both weather and climate. the influence of these elements differs from place to place and time to time.

it may be restricted to a small area and for a small duration of time,




we very often describe the influence of weather elements in name of weather such as sunny, hot, warm, cold, fine depending upon the dominant element of weather at a place and point in time.

therefore, the weather is the atmospheric condition of a place for a short duration with respect to its one or more elements.

two places even a short distance apart may have different kinds of weather at one and the same time




 Importance of weather:

a)Good weather improves people’s lives

b)Weather determines the kind of clothing to be worn by people in an area.

c)Knowledge of the weather of a place enables people to carry out economic activities which can be sustained by the weather in that place. e.g. dairy cattle do well in a cool and wet place.

d) By studying the weather of a place over a long time, we can establish its climate.




Weather and Human activities

Most human activities affected by weather that is experienced  at a place.For example, When the rains are heavy, flooding occurs and causes damage to crops, animals and infrastructure like roads. This means that few economic activities can take place.
When there is no rain, plants and animals die, rivers and streams dry up, and irrigation and other economic activities like fishing cannot be carried out. Therefore weather affects the social economic activities of a place.

Elements of Weather

Are the basic atmospheric condition of a place at a given time.
There are 7 element of weather

i)    Sunshine




ii)   Temperature

iii)   Humidity

iv)   Cloud cover

v)    Precipitation

       vi)    Wind

      vii)   Atmospheric pressure

IMPORTANCE OF EACH ELEMENT  OF WEATHER

i. Sunshine

Sunshine refers to the sun’s rays that reach the surface of the earth.

           Importance of Sunshine:




The sun’s energy enables plants to manufacture food through the process of photosysnthesisPeople need sunshine to dry their crops, food like cassava, millet, maize and fishThey also use sunshine to warm themselves

Dries clothes after washing them

ii. Temperature

Refers to how hot or cold an object or place is.
The heat in the atmosphere is supplied by th sun

Importance of Temperature:
  • Warm is essential for plant and animal survival
  • Plants need warm in order to manufacture their fool
  •  Facilitates formation of clouds




iii. Humidity

Is the amount of water vapor(moisture) in the atmosphere
There are two types of humidity:

a) Absolute humidity and

b) Relative humidity

Absolute humidity:

Is the actual amount of water vapor or moisture in a given volume of air at a particular temperature.

Relative humidity:




    Is the ratio of the actual amount of water vapor or moisture in a given volume of air (i.e. absolute humidity) to the maximum amount of water vapor that the same volume of air can hold at the same temperature.

iv. Cloud cover

Clouds are masses of tiny droplets of water or ice particles or both which are suspended in the atmosphere.
They are formed when water vapor or moisture in the atmosphere cools and condenses.

Importance of cloud cover:

    Are important because they condense to form rain and other forms of precipitation.

v. Precipitation




This refers as the fall or deposition of moisture water vapor or frozen water from the atmosphere onto the earths surface.

Importance of Precipitation:

All life on the earth is purely dependent on moisture provided through precipitationThe importance of rain is that,  rain provides water for plants to grow (i.e. water for irrigation, growth of grass and pasture depend on rain)Also animals too need water to drink and human needs for domestic and industrial uses.

Note:

Excess rain and rainstorms result in disasters due to flooding




vi. Wind

   Wind is air in motion. It is made up of variety of gases, such as oxygen and carbon dioxide. Wind move horizontally from areas of high pressure to areas of low pressure.

Importance of wind:

They are important in many aspects of weather for instance they cause flow of heat and moisture  and their transfer from one point to another and are also responsible for the movement of clouds.

Wind direction and wind speed or velocity are two important aspects in geography. Wind direction is important because it help us to understand characteristics of the particular winds in terms of temperature and moisture content.




Wind speed or velocity determines wind strength or force and therefore determines weather conditions of a place.

Example, When strong winds blow over a place, little or no rainfall will be experienced.

vii. Atmospheric Pressure

This is the force at a point on the earth’s surface due to the weight of air above that point. The atmosphere is the air surrounding earth’s surface and it has weight, which is force with which it presses down on a unit area. The weight of atmosphere on the earth’s surface and at sea level at 1033.3g/cm2




-Areas of very low pressure cause feeling of weightlessness and that is the feeling one gets when he or she is on top of a very high mountain like Mt Kilimanjaro.

-Areas under very low pressure may experience very strong winds periodically as air flows into such areas from high pressure regions.

CLIMATE

Climate is defined as a generalized or average condition of the weather of a place or region. the average weather condition is taken over a long period not less than 30 years of time to establish the climate of the place.
Or




is composite or generalized of the variety of day to day weather conditions.

Climate is defined as generalized or average condition of weather of a place or region. the average of weather condition is taken over a long period not less than 30 years of time to establish the climate of the place.

Difference between weather and climate

weather is an instantaneous physical state of the atmosphere at a particular place and time while Normal physical state or generated condition of the atmosphere or long-term average condition of a place. the period over which the climate is determined is at least 30 years

Weather changes refer to the specific instant of time( day or week). weather changes can occur within a short period of time that is from one minute to another or within an hour while climate change is generalized over a longer span of time and for a longer area. climate change occurs slowly over years and can have a detrimental impact on both environment and economic activities. for example, the recent increase in temperature has led to the melting of ice caps leading to an increase in the sea level




weather is expressed in terms of numerical values of meteorological elements whereas climate is expressed in terms of time averages and area averages of meteorological elements.

Weather is measured in the observatory. So the observatory must be at a place for which weather is to be described while climate is derived information on a regional basis. So scripts of observatories extending over a region are necessary.

Adverse weather results in crop failure or loss and warrants short-term contingent planning while adverse climate is considered in long terms agricultural planning.




Weather can be categorized as fair, unfair, excellent, etc. while climate is classified as desert climate, marine climate, tropical climate, etc.

The weather decides the success or failure of a crop in a particular season. while Climate decides the type of crop suitable for a region, while introducing new crops climate is considered

The weather of two places having the same numerical value must be the same while The climate of the two places having the same averages of weather can not be the same because their distribution over the years may be different




weather provides meteorological information while climate constitutes geographical information in respect of weather.

in weather, No statistical treatment is applied to the meteorological elements. They are used as observed and hence always changing. while in climate Application of statistical method over a longer period I did. It is more or less stable with few random changes

Advantages and disadvantages of weather forecasting

Weather forecasting is the prediction of the state of the atmosphere in a particular region over a period of 24 to 48 hours.

Weather forecasting is done almost daily by various authorities given the power to do so by the government, for example in Tanzania weather forecasting is performed by Tanzania meteorological authority.




advantages of weather forecasting

Military personnel benefit from weather forecasting as they can plan their military activities based on expected weather conditions. During the war the military can plan their battles by featuring in the expected weather condition to maximize the chance of winning the war.

Weather forecasting enable people to plan and take precautions against various natural calamities such as flood and typhoon so that to minimize their effects; bad weather such as torrent rainfall or strong wind can destroy properties and lead to death therefore if there is prediction that bad weather is going to happen people can take precaution such as evacuating from affected areas or staying indoors.




Weather forecasting enables farmers to adjust their farming activities to suit the expected weather condition. For example, if it is expected that there will be less rainfall in the future then farmers will prepare an irrigation system to compensate for the shortfall. 

help surfers to know when huge waves are expected

Weather forecasting greatly influences transport, especially in air and water. Aircraft take-off and landing can be affected by weather whereas storms and strong winds greatly affect water travel.




The weather forecast can help to guide and encourage tourists to visit certain areas. For example,  if it is predicted that certain areas will be warm in the future then tourists from cold areas will travel to this area to enjoy the forecasted warmth.

international trade of foodstuffs such as wheat, corn (maize), beans, sugar, cocoa and coffee can be severely affected by weather news. for example in 1975 a severe freeze in brazil caused the price of coffee to skyrocket within just few weeks. in addition, extreme heat and drought can affect production; one study estimate that 9 to 10 percent of cereal crop between 1964 and 2007 were lost to these phenomena. weather forecasting organizations are thus frequently called upon by banks and commodity traders to give them advance information on the possibility of such sudden changes.




disadvantages of weather forecasting

  • weather is extremely difficult to forecast correctly
  • it is expensive to monitor so many variables from som amny sources
  • the computers needed to perform the millions of calculations necessary are expensive
  • the weather forecasters get blamed if the weather is different from the forecast

methods and instruments used in weather forecasting

RADIOSONDE

This is an instrument used to register pressure and temperature from the ground to roughly 12 km above the ground.

The instruments are fixed to balloons filled with helium gas and are released into the atmosphere every day at a particular time from different weather stations.




The radiosonde transmits radio signals to computers on the ground station where they are analyzed.

The signals transmitted give to pressure, temperature, and humidity readings at different altitudes.

These balloons are made in such a way that they burst when they reach a certain altitude.

SATELLITES

The satellites used for predicting weather are human-made. Satellites are large electronic devices that are sent into space.




They move around the earth so that they can provide various types of information.

They are also used in radio, television, and telephone communication. Satellites transmit photographs on weather conditions on daily basis.

The movement of clouds can be predicted from an analysis of the movement of winds for a period of 24 hours.

PERSISTENCE METHOD

This is the simplest way of making a weather forecast. It assumes that the atmospheric conditions of a place at the time of forecast will not change.




For example, if it is 28 degrees Centigrade in Dodoma today, the persistence method predicts that it will still be 28 degrees centigrade in Dodoma tomorrow.

If two inches of rain fell in Arusha yesterday, this method predicts that two inches of rain will fall in  Arusha today.  

 This is the simplest way of making a weather forecast. It assumes that the atmospheric conditions of a place at the time of forecast will not change
Photo by Brett Sayles on Pexels.com

STATISTICAL FORECASTING

In this method, meteorologists ask themselves: How is the weather usually like at this time of the year? They then collect records of average temperatures and rainfall over the last few years.




This gives forecasters an idea of what the weather is ‘’supposed to be like’’ at a certain time of year.

There are other more complex methods of forecasting weather, including the use of computers and other technologies.




Relationship between Climate and Human Activities

Climate has many impacts on human activities. Various economic activities conducted by a man in different parts of the world are governed by the type of climate experienced in a particular region.

For example, people living in deserts and semi-arid regions do not practice much agriculture because their environment does not favour crop cultivation or animal husbandry.

In these regions, however, very limited agriculture and animals rearing is conducted. The animals kept include camels, goats, sheep, donkeys, and other hardy animals. Only drought-resistant crops such as dates are grown in deserts and arid areas. In tropical and equatorial regions, a lot of agriculture is carried out.




The inhabitants of these regions take part in the cultivation of crops and the keeping of animals. Crops grown include cocoa, banana, horticultural crops, and grains. The animals kept in these climatic zones include cattle, pigs, donkeys, horses, poultry, and other farmyard animals.

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