ELEMENTS OF CLIMATE AND WEATHER (1) - Himachal Pradesh PCS Free Notes

ELEMENTS OF CLIMATE AND WEATHER

Climate is decided by a region’s climate system. A climate system has few major components: the atmosphere, the layer, the cryosphere, and the land surface. The atmosphere is that the most variable a part of the climate system. The composition and movement of gases encompassing the planet will change radically, influenced by natural and man-made factors.

Climate attributes

The most acquainted options of a region’s climate area unit in all probability average temperature and precipitation. Changes in every day, day-to-night, and seasonal differences additionally facilitate confirm specific climates. For instance, San Francisco, California, and Beijing, China, have similar yearly temperatures and precipitation. However, the daily and seasonal changes create San Francisco and Beijing very totally different. San Francisco’s winters don’t seem to be a lot of cooler than its summers, whereas Beijing is hot in summer and cold in winter. San Francisco’s summers are dry and its winters are wet. Wet and dry seasons are reversed in Beijing—it has rainy summers and dry winters.

Climates have features which conjointly embody breeziness, humidity, cloudiness, atmospheric pressure, and fogginess. Latitude plays an enormous factor in deciding climate. Landscape may also facilitate outline regional climate. A region’s elevation, proximity to the ocean or freshwater, and land-use patterns will all impact climate.

All climates are the product of the many factors, as well as latitude, elevation, topography, distance from the ocean, and location on a continent.

Of the varied environmental condition components, temperature, precipitation, pressure and winds are the foremost necessary owing to their way reaching international influences. These components and their distribution, whether or not horizontal from equatorial to polar regions, or vertical from ground to atmosphere, are in a way or another full of some or all of the environmental condition factors: latitude, altitude, continentality, ocean currents, insolation, prevailing winds, slope and facet, natural vegetation and soil.

Temperature

Importance of temperature

1. Temperature influences the particular quantity of water vapor present within the air and therefore decides the moisture-carrying capability of the air.

2. It decides the speed of evaporation and condensation, and so governs the degree of stability of the atmosphere.

3. As relative humidity is directly associated with the temperature of the air, it affects the character and kinds of cloud formation and precipitation.

Temperature is the degree of hotness or coldness of an object. We tend to observe one thing feeling hot (like the soup we drink when were sick) or cold (like the snow, particularly if one is not carrying gloves), were talking regarding temperature.

The temperature of an object, typically measured in degrees-Fahrenheit or degrees-Celsius, tells us what quantity heat, or energy, the item has.

Factors Influencing Temperature

The six broad factors affecting temperature of regions are viz. Latitude; Altitude; Continentality; Ocean currents and Wind; Slope, shelter and aspect; and Natural Vegetation and Soil.

Latitude

The mid-day sun is sort of overhead inside the tropics; however outside the tropics the sun’s rays reach the earth at an angle.
Temperature therefore diminishes from equatorial regions to the poles. Bands of rays coming back from the sun to 2 totally different latitudes on the earth’s surface.
Band b falls vertically over the equatorial latitudes on equatorial surface E. Band a falls obliquely over the temperate latitudes on surface T.

Travels through a shorter distance and its focused solar insolation heats up a smaller surface areal temperature in therefore high.

Travels through a extended distance and far of its heat is absorbed by clouds, water vapor and dirt particles. Its oblique ray has to heat up a large are; temperature is thus low.

Altitude

Since the atmosphere is principally heated by conduction from the planet, it may be expected that places nearer to the earth’s surface are warmer than those in a higher place.

Thus temperature decreases with increasing height on top of water level. This rate of decrease with altitude (lapse rate) is rarely constant, variable from place to position and from season to season.

But for all sensible functions, it should be reckoned that a fall of 1deg F happens with an ascent of 300 feet or 0.6 deg C. per one hundred metres. It is sometimes a lot of in summer than in winter.

For example in temperate latitudes, in summer, an ascent of solely 280 feet can cause the temperature to drop by one degree F., whereas in winter it needs four hundred feet.

Similarly, the lapse rate is bigger by day than in the dark, larger on elevated highlands than on level plain.

In tropical countries wherever the ocean level is 80 deg F., a city that’s situated at a height of 4,500 feet can record a mean temperature of 65 deg F.

Continentality

Land surfaces are heated a lot of quickly than water surfaces, attributable to the upper heat of water.
In different words, it needs solely one-third the maximum amount energy to lift the temperature of a given volume of land by 1 deg F, because it will for an equal volume of water.
This accounts for the warmer summers, colder winters and larger range of temperature of continental interiors as compared with maritime districts.

Ocean Currents and Wind

Both ocean currents and winds have an effect on temperature by transporting their heat or coldness into adjacent regions.

Ocean currents just like the Gulf stream or the North Atlantic Drift heat the coastal districts of Western Europe keeping their ports ice- free.

Ports set within the same latitude however washed by cold currents, like the cold currents, like the cold geographical area Current off north-east Canada, area unit frozen for many months.

Cold currents additionally lower the summer temperature, notably after they area unit carried landward by on-shore winds. On the opposite hand on-shore Westerlies, convey a lot of tropical heat air to temperate coasts, particularly in winter.

The Westerlies that come back to Britain and Norge tend to be cool winds in summer and heat winds in winter and area unit most useful in analgesic the climate.

Local winds, e.g. Foehn, Chinook, Sirocco, Mistral, additionally manufacture marked changes in temperature.

Within every ocean left light arrow shows indicate heat currents, whereas right light indicates cold currents.

Mountain ranges that have an east-west alignment just like the Alps show a better temperature on the south-facing ‘sunny slope’ than the north facing ‘sheltered slope’.

The bigger insolation of the southern slope is best suited to vine cultivation and features a additional flourishing vegetative cover. Consequently, there are a lot of settlements and it’s higher utilised than the ‘shady slope’.

A steep slope experiences a more speedy amendment in temperature than a mild one.

In mountainous areas a hot day followed by calm, clear night during which the air cools faster over the upper slope might induce cold, significant air to blow down the slope and accumulate at the depression bottom pushing the hotter air upwards.

The temperature might then be lower within the valley than above because the slopes. A reversal of the lapse rate has taken place. this can be referred to as a temperature inversion.

Natural vegetation and soil

There may be a definite distinction in temperature between wooded regions and open ground.

The thick foliage of the Amazon jungle cuts off a lot of the in- coming back insolation and in several places daylight never reaches the bottom. It is; in fact, cool within the jungle and its shade temperature could be a few degrees under that of open areas in corresponding latitudes.

During the day trees lose water by evapo – transpiration in order that the air on top of is cooled.

Relative wetness will increase and mist and fog might kind.

Light soils replicate additional heat than darker soils that area unit higher absorbers. Such soil variations might bring about to slight variations within the temperature of the region.

As an entire, dry soils like sands area unit terribly sensitive to temperature changes, whereas wet soils, like clay, retain a lot of wetness and heat up or relax additional slowly.

Precipitation

Types of Precipitation.
If air is sufficiently cooled below dew-point, little drops of vapour can condense around dirt particles.
When they float regarding as plenty of minute water droplets or ice crystals at a substantial height on top of water level, they kind clouds- cirrus, cumulus or stratus cloud.
When condensation happens at ground level haze, mist or fogs are shaped.
In higher latitudes or altitudes, wherever condensation of vapour might occur within the atmosphere at temperatures below freezing-point, snow falls, either as feathery flakes or individual ice crystals.
If the damp air ascends speedily to the cooler layers of the atmosphere, the water droplets freeze into ice pellets and fall to the world as hail or hailstones.
As more and more super-cooled water drops accumulate around a water ice, it will increase steady in size; a number of them weigh the maximum amount as 2 pounds.
In a severe hail-storm the hailstones do great harm to crops and buildings.
Very typically, the ice-pellets exist as frozen rain-drops, melting and re-freezing on their manner down; this forms sleet. only if droplets coalesce into 0.2mm-6mm size.

Rainfall

There are 3 major sorts of precipitation.

Convectional precipitation.
This form of precipitation is most typical in regions that area unit intensely heated, either throughout the day, as within the tropics, or within the summer, as in temperate interiors.
When the earth’s surface is heated by physical phenomenon, moisture-laden vapour rises as a result of heated air continually expands, and becomes lighter.
Air rises during a convection current when a chronic amount of intense heating.
While ascending, its vapour condenses into thundercloud clouds with an excellent vertical extent.
Hot, rising air has nice capability for holding wetness that is lush in regions of high ratio.
As the air rises it cools and once saturation is reached torrential downpours occurs, typically in the midst of thunder and lightning.
The summer showers in temperate regions area unit equally significant with occasional thunderstorms.
These downpours might not be entirely helpful for agriculture as a result of the rain is therefore intense that’s doesn’t sink into the soil however is drained off quickly.

Orographic or Relief rain.

Unlike convectional rain that is caused by convection currents, Orographic rain is made where damp air is forced to ascend a mountain barrier.
It is best developed on the windward slopes of mountains wherever the prevailing moisture-laden winds come back from the ocean.
The air is compelled to rise, and is thereby cooled by growth within the higher altitudes and therefore the subsequent decrease in air pressure.
Since it’s caused by the relief of the land, it’s conjointly called relief rain.
Much of the precipitation older on the windward slopes of the north-east of West Malaysia, western New Zealand, western New Zealand, western Scotland and Wales and therefore the Assam hills of the Indian sub-continent is relief rain.
On descendent the leeward slope, a decrease in altitude will increase each the pressure and therefore the temperature; the air is compressed and warm.
Consequently, the ratio can drop. There’s evaporation and tiny or no precipitation. Space| within the lee of the hills is termed the country area.
The effects of country area unit felt on the Canterbury Plain of South Island, New Zealand and therefore the western slopes of the Northern and Central Andes and in several different areas.

Cyclonic or frontal rain.

This form of rain is independent of relief or convection.
It is only related to cyclonic activity whether or not within the temperate regions (depressions) or tropical regions (cyclones).
Basically it’s attributable to the convergence (meeting) of 2 completely different air lots with different temperatures and alternative physical properties.
As cold air is denser, it tends to stay near the bottom. The nice and cozy air is lighter and tends to rise over the cold air.
In ascent pressure decreases, the air expands and cools, condensation takes place and light showers known as cyclonic or frontal rain occur.