Weather and ClimateBY URJA, CHANI, MEGHNA AND AYAAN

Vocabulary

Adiabatic cooling/heating The rate of cooling (by expansion) as an air parcel rises. It is approximately 1 degrees Celsius per 100 meters. It is also the rate of heating (by compression) as an air parcel descends.

Air mass A large body of air that has similar temperature, pressure and moisture properties.

Anticyclone High pressure system in which air descends to give calm conditions and clear skies. Associated with summer heat waves and winter frosts and fogs.

Atmosphere The envelope of air surrounding the Earth and bound to it by gravity.

Atmospheric pressure: Pressure (force per unit area) exerted by the atmosphere on any surface by virtue of its weight.

Vocabulary

Climate Long-term (50 year) weather averages.

Continental climate A climate with a high temperature range away from the influence of the sea. Winters will be colder and summers warmer compared to a coastal location for the same latitude.

Areas of Low Pressure/Depression (cyclone, low, low-pressure area) Area in the atmosphere in which the pressures are lower than those of the surrounding region at the same level. In its development a depression usually has the following phases. A wave (young) depression forms and moves along a front. Mature depressions have well-developed warm sectors and both cold and warm fronts. An occluded depression is that within which there has developed an occluded front.

Vocabulary

Evaporation The physical process by which a liquid or solid substance is transformed to a gas; the opposite of condensation.

Fog Saturated air with visibility below one kilometre. Fog differs from cloud only in that the base of fog is at the Earth's surface while clouds are above the surface.

Front The meeting point between two air masses of different density. Since the temperature is the most important regulator of the atmosphere density, a front almost invariably separates air masses of different temperature. When warmer air replaces the colder, it is a warm front, and a front is a cold one when the opposite occurs.

Humidity Water vapor content of the air.

Maritime climate  A climate with a low temperature range influenced by proximity to the sea. Winters will be warmer and summers cooler compared to a continental location for the same latitude.

Vocabulary

Precipitation Any of all of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground. The forms of precipitation are: rain, drizzle, snow, snow grains, snow pellets, diamond dust, hail, and ice pellets.  

Prevailing wind The most common wind direction for a particular location.

Rain Shadow The dry region on the leeward side of a mountain (the side sheltered from the wind).

Relief rainfall Formed when air is forced to rise over relief features such as hills or mountains. Cooling and condensation occurs as the air rises.

Seasonality Periodic fluctuations in the climate related to seasons of the year e.g. wet winters, drier summers.

Smog A word currently used as a synonym for general air pollution. It was originally created by combining the words "smoke" and "fog."

Vocabulary Synoptic chart A weather chart reflecting the state of the atmosphere over a large area at a given moment.

Temperature A physical quantity characterizing the mean random motion of molecules in a physical body. In other words, it is a measure of the degree of hotness or coldness of a substance.

Temperature range Maximum minus the minimum temperature for a particular location.

Warm front The forward edge of an advancing warm air mass that is rising over cooler air in its path.

Warm sector The zone of warm air within a depression.

Water vapor Water substance in vapor (gaseous) form; one of the most important of all constituents of the atmosphere.

Weather The state of the atmosphere, mainly with respect to its effects upon life and human activities. As distinguished from climate, weather consists of the short-term (minutes to about 15 days) variations of the atmosphere state.

Wind movement of air caused by changes in temperature and air pressure. Winds are always identified by the compass direction from which they blow.

Precipitation example

The science of monitoring and studying the atmosphere and predicting its weather and climate is called meteorology

Seasons

Seasons

Winter- It is the coldest season of the year in polar and temperate climates. It is caused by the axis of the Earth in those hemispheres being positioned away from the sun  

Seasons

Spring- Spring occurs after the winter season, and before summer. This is the season where vegetation appears for the northern hemisphere, which is march to may, and vegetation for the southern hemisphere happens in September to November

Seasons

Summer- Is the warmest season of the year, it occurs in the northern hemisphere from June to August. and in the southern hemisphere during December and February.

Seasons

Monsoon- Monsoon is a term that is used in meteorology to signify a seasonal reversal of wind direction.  

Autumn

Autumn- The season after summer and before winter. Which occurs in the northern hemisphere from September to November, and in the southern hemisphere from March to May.

Climate

Climate- it is the average weather in a place over many years. Weather changes daily whereas   climate changes over the years.

In an average year the climate in a tropical rainforest is very humid due to all the rainfall. These types of climates are found near to the equator because there is direct sunlight.

The climate in tropical desserts are very dry and hot, and has hardly any rainfall. October is recorded as the hottest month over the years.

Case Studies

During December 2010 winds from the north east brought cold arctic air and snow. Scotland and North East England were significantly affected, with snow 50 cm deep in places. Temperatures were mainly below 0°C, making it the coldest December in the last 100 years.

The impacts were:• Roads were closed. People were stranded in their cars overnight on the M8 and A9 in

Scotland.• Airports closed, including Heathrow and Gatwick, disrupting travel plans over

Christmas.• Schools closed.• On 20 December the AA reported its busiest-ever day because of car breakdowns.• More people than usual were admitted into hospital because of accidents and falls.• Emergency services and local authorities were all put under pressure.• After areas thawed, there were problems with burst water pipes. In Northern Ireland

40,000 homes were without water

Africa

Africa is at risk from climate change. Observed temperatures have showed a warning since 1960s suggesting that the annual temperature in the region will rise by 3.4 degree Celsius.

This will cause the annual rainfall to decrease, causing higher rainfall in the northern region.

Mozambique: 2007 floods and cyclone“The magnitude of the cyclone and floods (together with drought conditions in the south of the country, which have not been part of the UN humanitarian response) all point to the effects of global warming. These natural disasters are growing more frequent and more severe with time, highlighting the importance of national preparedness to reduce the vulnerability of the population to such events and minimize their impact.” 

By the end of February 2007, Mozambique was reeling from the double impact of two disasters. While Zambezi and Save rivers were already flooded, a Category four cyclone brought more rain and destroyed southern coast.

“The village of Tebunginako on the island of Abaiang is a barometer for what Kiribati can expect in the future. The community has had to relocate due to the effects of severe coastal erosion and saltwater intrusion. These impacts are already felt on the atolls of Kiribati and will be exacerbated by the effects of climate change.”

Over the past 40 year the sea level has risen, storm surges have become more powerful and tides more forceful. Eventually the erosion was so great that the village had to be abandoned.

The access salt is effecting the area. The fresh water milkfish, that once fed the village is long gone. The pant life is fatally overdosing on salt.

Each year villagers head further into the island to find fresh food and water, but the island can only go back so far.

”It is very difficult to find food these days,” Mr Maroieta says. ”It makes us feel sad that there is nothing left of our village. This is the place of our ancestors and we feel threatened and vulnerable.”

Tebunginako Village

Cyclones

Cyclones - a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth. Most large-scale cyclonic circulations are centered on areas of low atmospheric pressure

Anti- Cyclones

Anticyclones- a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere, counterclockwise in the Southern Hemisphere

Wind Currents

Wind Currents - Winds are named by the direction from which they blow. The globe is encircled by six major wind belts, three in each hemisphere. From pole to equator, they are the polar easterlies, the westerlies, and the trade winds. All six belts move north in the southern summer and south in the northern winter.

Wind Currents

Wind Currents - Winds are named by the direction from which they blow. The globe is encircled by six major wind belts, three in each hemisphere. From pole to equator, they are the polar easterlies, the westerlies, and the trade winds. All six belts move north in the southern summer and south in the northern winter.

The Green house affect

Types of Rainfall

Types of Rainfall - convection rainfall: Convectional rainfall occurs when the energy of the

sun (or insolation) heats the earth’s surface and causes water to evaporate changing to water vapor

Relief rainfalls

Relief rainfall usually takes place around coastal areas where a fleet of hills runs along to the coast. When wet onshore wind from the sea meet a mountain, hill and barrier, it is forced to rise along the slope and cools.