WEATHER SYSTEMSWEATHER SYSTEMS

WEATHER AND CLIMATEWEATHER AND CLIMATE

WeatherWeather

Weather describes the conditions of the Weather describes the conditions of the atmosphere at a particular time.atmosphere at a particular time.

Climate describes the long term Climate describes the long term atmospheric characteristics. It deals with atmospheric characteristics. It deals with average figures of each element over a average figures of each element over a period of time, (e.g. average monthly period of time, (e.g. average monthly temperatures) etc.temperatures) etc.

What is WeatherWhat is Weather

Weather describes whatever is happening Weather describes whatever is happening outdoors in a given place at a given time. Weather outdoors in a given place at a given time. Weather is what happens from minute to minute. is what happens from minute to minute.

The weather can change a lot within a very short The weather can change a lot within a very short time. For example, it may rain for an hour and then time. For example, it may rain for an hour and then become sunny and clear. become sunny and clear.

Weather includes daily changes in precipitation, Weather includes daily changes in precipitation, barometric pressure, temperature, and wind barometric pressure, temperature, and wind conditions in a given location. What is your conditions in a given location. What is your weather like today?weather like today?

What is your weather like today?What is your weather like today?

Which picture describes your weather Which picture describes your weather today?today?

What is ClimateWhat is Climate

Climate describes the total of all weather Climate describes the total of all weather occurring over a period of years in a given occurring over a period of years in a given place. This includes average weather place. This includes average weather conditions, regular weather sequences (like conditions, regular weather sequences (like winter, spring, summer, and fall), and winter, spring, summer, and fall), and special weather events (like tornadoes and special weather events (like tornadoes and floods). Climate tells us what it's usually like floods). Climate tells us what it's usually like in the place where you live. in the place where you live.

DIFFERENCES BETWEEN THE DIFFERENCES BETWEEN THE TWOTWO

Weather is the actual conditions in the Weather is the actual conditions in the atmosphere at a particular place and time atmosphere at a particular place and time over a twenty four hour period.over a twenty four hour period.

Climate is the average atmospheric Climate is the average atmospheric conditions a place gets based on a period of conditions a place gets based on a period of over thirty years.over thirty years.

The climate of a place is described as its The climate of a place is described as its average weather conditions.average weather conditions.

Caribbean weather systemsCaribbean weather systems

A weather system is a large area of the A weather system is a large area of the atmosphere that has special temperature atmosphere that has special temperature and moisture conditions.and moisture conditions.

INTER TROPICAL CONVERGENCE ZONEINTER TROPICAL CONVERGENCE ZONE TROPICAL WAVESTROPICAL WAVES HURRICANESHURRICANES COLD FRONTSCOLD FRONTS ANTICYCLONESANTICYCLONES

I.T.C.ZI.T.C.Z

The ITCZ is an area of low pressure lying The ITCZ is an area of low pressure lying east to west across the equatorial region.east to west across the equatorial region.

The hot air from the north east trade winds The hot air from the north east trade winds meet the hot air from the south east trade meet the hot air from the south east trade winds in this region.winds in this region.

The hot moist air is forced to rise, resulting The hot moist air is forced to rise, resulting in rainfall.in rainfall.

This belt of low pressure moves north and This belt of low pressure moves north and south of the equator with the seasons.south of the equator with the seasons.

I.T.C.ZI.T.C.Z

I.T.C.ZI.T.C.Z

In June it drifts northwards and may affect In June it drifts northwards and may affect Trinidad and Tobago and the rest of the Trinidad and Tobago and the rest of the southern Caribbean.southern Caribbean.

In December it drifts south and affects In December it drifts south and affects Guyana. It is also active in March and Guyana. It is also active in March and September when the hottest place is the September when the hottest place is the equator.equator.

Conditions associated with the Conditions associated with the I.T.C.ZI.T.C.Z

Heavy rainfallHeavy rainfall Overcast skies with cumulus cloudsOvercast skies with cumulus clouds Light and calm windsLight and calm winds High temperaturesHigh temperatures

ITCZITCZ

Tropical WavesTropical Waves

They are weak, low pressure systems that They are weak, low pressure systems that lack a closed centre.lack a closed centre.

They form near Africa over the warm waters They form near Africa over the warm waters of the Atlantic Ocean and move westwards of the Atlantic Ocean and move westwards into the Caribbean.into the Caribbean.

They affect most of the islands of the They affect most of the islands of the Caribbean during the months of June to Caribbean during the months of June to December.December.

Tropical WavesTropical Waves

Conditions associated with Conditions associated with Tropical WavesTropical Waves

Moderate windsModerate winds Heavy and continuous rainfallHeavy and continuous rainfall Overcast skiesOvercast skies High temperatures.High temperatures.

Tropical waves can eventually develop into Tropical waves can eventually develop into hurricanes. They are not hurricanes since hurricanes. They are not hurricanes since they don’t have a low pressure centre and they don’t have a low pressure centre and strong winds.strong winds.

Tropical WavesTropical Waves

HurricanesHurricanes

HurricanesHurricanes

Hurricanes are strong , low- pressure Hurricanes are strong , low- pressure systems with strong winds of > 120 km per systems with strong winds of > 120 km per hour.hour.

Winds blow into them in an anti-clockwise Winds blow into them in an anti-clockwise direction with heavy rainfall.direction with heavy rainfall.

They start off as tropical waves near Africa They start off as tropical waves near Africa and move into the Caribbean during June to and move into the Caribbean during June to December.December.

HurricanesHurricanes

Warm ocean water >26 degrees celsius.Warm ocean water >26 degrees celsius. Coriolis effect north and south of latitudes Coriolis effect north and south of latitudes

10 degrees north and south, this causes the 10 degrees north and south, this causes the spiral motion of the hurricane and influences spiral motion of the hurricane and influences its path.its path.

Divergent upper level winds allowing Divergent upper level winds allowing updraughts of air.updraughts of air.

Most Caribbean islands are affected by Most Caribbean islands are affected by hurricanes.hurricanes.

HurricanesHurricanes

HurricanesHurricanes

Wind speeds above 120 km/ hour.Wind speeds above 120 km/ hour. Wind direction varying between north east and Wind direction varying between north east and

south east.south east. Torrential rainTorrential rain Overcast skies with towering cumulonimbus Overcast skies with towering cumulonimbus

clouds.clouds. Thunderstorms with lightning.Thunderstorms with lightning. Temperatures remain high averaging 27 degrees Temperatures remain high averaging 27 degrees

celsius.celsius.

HurricanesHurricanes

Cold FrontsCold Fronts

A front is an area where two air masses of A front is an area where two air masses of different temperatures meet.different temperatures meet.

Cold dry air moves south from the North Cold dry air moves south from the North American continent and pushes under the American continent and pushes under the warm, moist Caribbean air.warm, moist Caribbean air.

The rising warm air cools and condenses The rising warm air cools and condenses resulting in heavy rainfall.resulting in heavy rainfall.

Weather Associated with Cold Weather Associated with Cold FrontsFronts

Cooler temperatures, Cooler temperatures, 18 – 21 degrees 18 – 21 degrees celcius.celcius.

Moderate rainfall that Moderate rainfall that lasts for days lasts for days depending on the depending on the movement of the movement of the frontal system.frontal system.

Moderate cloud coverModerate cloud cover Winds from the north.Winds from the north.

AnticyclonesAnticyclones

Anticyclones are high pressure systems.Anticyclones are high pressure systems. Winds blow out of them in an anti- clockwise Winds blow out of them in an anti- clockwise

direction.direction. They form around mid- latitudes and may They form around mid- latitudes and may

drift into the Caribbean. They are stable with drift into the Caribbean. They are stable with sinking air blowing out of the centre.sinking air blowing out of the centre.

They affect most of the Caribbean north of They affect most of the Caribbean north of Trinidad and Tobago.Trinidad and Tobago.

AnticyclonesAnticyclones

Weather associated with Weather associated with anticyclonesanticyclones

Dry and sunnyDry and sunny Clear skiesClear skies Moderate windsModerate winds Moderate temperaturesModerate temperatures