Grade 7 Geography: Climate and Weather Chapter

ICSE Grade 7 Geography

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Grade 7 Geography: Climate and Weather Chapter 作者: Mind Map: Grade 7 Geography: Climate and Weather Chapter

1. meteorology

1.1. study of

1.1.1. weather

1.1.2. its elements

2. diff b/w weather and climate

2.1. weather

2.1.1. short term atmospheric conditions

2.1.2. existing in a given time given area / particular statuion

2.1.3. can change in a short period

2.1.4. influenced by temperature humidity

2.2. climate

2.2.1. aggregate over long period of time

2.2.2. day to day weather conditions

2.2.3. refers to a large area

2.2.4. collective effect of all its elements

3. elements of weather and climate

3.1. 1. temperature

3.1.1. heating of earth and atmosphere solar radiation is the only permanent and continuous source of heat process of giving out energy by the sun insolation amt of solar radiation received on earth's surface received as short waves does not heat the atmosphere varies from place to place, depends on terrestrial radiation heat is reflected back by the earth's surface long wave radiations heats up the atmosphere

3.1.2. measurement measured with the help of a thermometer made out of glass tube mercury in it which expands on heating and contracts on cooling scale of a thermometer Six's thermometer types daily range Average / mean temperature annual range

3.1.3. isotherms lines imaginary lines drawn to connect location having same temperature

3.2. 2. atmospheric pressure

3.2.1. force exerted by vertical column of air per unit of surface area

3.2.2. air has weight due to great height of atmosphere

3.2.3. factors effecting altitude pressure exerted decreases with increase in height decrease by 1 cm of mercury per 110 metres of ascent highest at sea level temperature decreases with increase in temperature

3.2.4. pressure belts created by (main factors) unequal heating of rotation of the earth typically high temperature low temperature permanent pressure belts Equatorial Low (doldrums) Sub Tropical High Sub Polar Low Polar High

3.2.5. measurement measured with the help of a barometer simple barometer aneroid barometer ranges measured in cm of mercury inches of mercury millibars (mb) altimeter height of an airplane during its flight barograph

3.3. 3. humidity

3.3.1. definition amount of water vapour in the air related to temperature of air

3.3.2. expressed as absolute humidity amount of water vapour per cubic metre of air e.g. 20 gm / cubic metre relative humidity ratio of expressed as % e.g. 25% air saturation

3.3.3. measurement relative humidity is most commonly used for measuring humidity saturated air has a relative humidity of 100% dry air has a relative humidity of 0% measured with the help of a hygrometer wet and dry bulb thermometer

3.4. 4. precipitation

3.4.1. process by which water falls down from the atmosphere to the earth no change of state of water, only location - from atmosphere to ground occurs when tiny droplets join to form larger droplets to fall to the ground

3.4.2. types of precipitation - determined by temperature inside and outside the clouds rain precipitation in liquid form most common form of precipitation hail precipitation in frozen lumps of ice form inside tall cumulonimbus clouds dew precipitation in tiny water droplets which condenses on cool surfaces occurs on calm clear cold nights snow precipitation in the form ice crystals at high latitude and mountain regions

3.4.3. rain is shown by isohyet imaginary line passes through places with same rainfall

3.4.4. how is rain shown on a map?

3.4.5. measurement measured by a rain gauge rain water collected through funnel for 24 hrs water measured with a measuring glass kept slightly above the ground (30 cm) measured in millimeters(mm) instrument providing continuous record of rainfall- hyetograph snow or hail measured by melting them into water

3.5. 5. wind

3.5.1. air which moves from places with high pressure to places with low pressure

3.5.2. characteristics direction speed

3.5.3. kinds of winds winds coming from the east are called easterly winds winds coming from the west are called westerly winds planetary winds winds that blow periodic /local/ regional winds winds that blow examples

3.5.4. measurement of wind direction and velocity direction of wind is found with a wind vane arrow of the wind vane points to the direction of wind velocity or speed is found with an anemometer measured in km/h nowadays for recording continuous wind velocity we use a anemograph anemograph records wind velocity continously

3.6. 6. clouds

3.6.1. definition large collection of very small droplets of water or ice crystals droplets are small and light enough to float in the air formed though evaporation and condensation

3.6.2. classification of clouds based on shape and height high clouds middle clouds low clouds