GEOGRAPHY EYA NOTES. Weather. atmosphere. Weather and climate

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1 GEOGRAPHY EYA NOTES Weather and climate Weather The condition of the atmosphere at a specific place over a relatively short period of time Climate The atmospheric conditions of a specific place over a considerable period of time (30-35 years) Weather - Temperature How hot or cold a place is - Relative humidity Amount of water vapor in the air High relative humidity body warm perspire Expressed as a percentage - Precipitation Water returning to the Earth s surface (rain, snow, frost, hail) - Wind Air moves as a result of differences in air pressure atmosphere - layer of air which surrounds the earth mixture of gases, water vapor and dust particles - prevents the earth from overheating in the day and losing too much heat in the end (regulates the temperature) - sub-divided into different layers

2 Troposphere Plonk Notes - Geography - Lowest layer of the atmosphere - 12km above sea level EARTH - Greatest concentration of gases, water vapor and dust particles - Changes in conditions of the troposphere results in changes in the weather elements of weather - temperature latitude altitude distance from sea cloud cover - relative humidity - precipitation temperature - degree of hotness and coldness of a place - affected by the amount of sun s rays (solar radiation) that reaches the earth s surface - amount of solar radiation is determined by factors latitude the distance to the north and south of the Equator increases as we move away from the equator to the poles temperature at the poles and equator are different because of the different angles at which the Sun s rays reach the Earth, thus the sun s rays are less intense at the poles than at the equator altitude the height of a point above the level of the sea s surface temperature of the earth s surface at different altitudes vary

3 temperature generally decreases with increasing altitude places near sea level are warmer because the Earth s surface absorbs heat from the Sun directly air at higher altitudes is thin (made up of smaller concentration of as, dust and water vapor than the dense air at sea level), and therefore it is unable to absorb heat as effectively as dense air at sea level because it has a smaller concentration of gases to trap heat distance from the sea land heats up and cools down more quickly than the sea o Maritime effect - Refers to the effect that large ocean bodies have on climate of coastal areas smaller temperature range - Summer: air over land heats up quickly while air over sea remains cool - Winter: air over sea relatively warm compared to air over land sea takes longer time to lose heat - Coastal areas would therefore experience cooler summers and warmer winters o Continental effect - Refers to the effect that continental surfaces have on climate of inland areas far away from the sea larger temperature range annually - Temperatures of inland areas are not affected by the sea - Inland areas would therefore experience warmer summers and colder winters Cloud cover Refers to the amount of clouds over an area

4 Effects the temperature by influencing the amount of solar radiation entering and leaving the atmosphere DAYTIME o No cloud cover: allows large amounts of solar radiation to reach Earth s surface temperature rise quickly o Cloud cover: reflects part of the incoming solar radiation back into outer space less solar radiation is absorbed NIGHTTIME o No cloud cover: allows heat from the Earth to escape into outer space easily sharp drop in temperature of the ground o Cloud cover: prevents heat from escaping into outer space keeps temperature of ground relatively high Relative humidity Humidity: Refers to the amount of water vapor present in the air Places nearer to the equator have higher humidity Relative humidity: refers to the proportion of water vapor present in the air in relation to the maximum amount the air can hold at a particular temperature (commonly expressed as a percentage) Saturation: air is carrying the maximum amount of water vapor it can hold at that temperature (100%) Factors affecting: large water bodies, thick vegetation High relative humidity more likely for rain to occur Precipitation Refers to water falling down from the atmosphere onto the Earth s surface Takes the form of rain, snow, frost or hail Types of rain: convectional rain and relief rain

5 o Convectional rain - Occurs when there is intense heating of the Earth s surface, which usually takes place in the morning and early afternoon - Earth s hot surface heats up, causing air to rise quickly condensation occurs and clouds are formed heavy rain falls, accompanied by thunder and lightning at the same time, warm air continue to rise and condense rain will ease when clouds lose their moisture - High temperatures in tropical areas increase the capacity to hold large amounts of water vapor convectional rain is very common because relative humidity is high - Falls over a small area - Heavy but short-lived o Relief rain - Occurs mainly in places where moist air from the sea is forced to rise above a highland such as a mountain range - Wind blows over water body picks up large amounts of water vapor relative humidity of air increases air rises and temperature falls air becomes saturated and form clouds relief rain drops when clouds can no longer hold water droplets rain falls on windward side of mountain - Leeward side of mountain receives little or no rain because the air that reach this side would have lost most or all of its moisture

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