SCIENCE 8 A/B LCDA. DIANA MONTERO

Factors that Influence Weather
There are many factor that influence weather, many of which we cannot see.
The Water CycleAs the sun warms the surface of the Earth, water rises in the form of water vapor from lakes, rivers, oceans, plants, the ground, and other sources. This process is called evaporation.
Water vapor provides the moisture that forms clouds; it eventually returns to Earth in the form of precipitation, and the cycle continues.
Air MassesWhen air hovers for a while over a surface area with uniform humidity and temperature, it takes on the characteristics of the area below. For example, an air mass over the tropical Atlantic Ocean would become warm and humid; an air mass over the winter snow and ice of northern Canada would become cold and dry. These massive volumes of air often cover thousands of miles and reach to the stratosphere. Overtime, mid-latitude cyclonic storms and global wind patterns move them to locations far from their source regions.
What happens when 2 air masses meet? The cold air pushes the hot air upwards, when going up the temperature drops and the air can't hold as much water when it is warm, so the cold water molecules condense and form clouds.
Jet StreamA jet stream is the name given to the area of air above where two air masses of different temperature converge e.g. a cold front meeting a warm front. The greater the temperature difference between the air masses, the greater the air pressure difference, and the faster the wind blows in the jet stream. This river of air has wind speeds which often exceed 100 mph, and sometimes over 200 mph. Jet streams more commonly form in the winter, when there is a greater difference between the temperature of the cold continental air masses and warm oceanic air masses.
This meandering current of high-speed wind, a jet stream is usually found around five to ten miles above Earth’s surface.
It generally flows west to east, often in a non-continuous wavy fashion, with cold, Equatorward dips and warm, Poleward bulges.
Weather FrontsThe transition zone between two air masses of different humidity and temperature is called a front. Along a cold front, cold air displaces warm air; along a warm front, warm air displaces cold air. When neither air mass displaces the other, a stationary front develops. Towering clouds and intense storms may form along cold fronts,
while widespread clouds and rain, snow, sleet, or drizzle may accompany warm fronts.
El Niño and La Nina
El Nino is caused by the periodic shift in wind speed and direction in the tropical eastern Pacific which leads to changes in sea Surface temperatures. In what scientists call El Niño events, prevailing easterly winds weaken or give way to westerly winds, and the normal upwelling process, which brings cool, nutrient-rich waters up from lower levels of the ocean, stops.
This causes sea surface temperatures to rise, providing an unfavorable habitat for many sea animals and fish. The warmer ocean conditions can also lead to more rainfall and floods along the west coast of the Americas. A stronger easterly wind flow, on the other hand, can increase upwelling and make the sea surface temperatures even colder, producing La Nina. Both phenomena can have far-reaching weather effects. For example, strong El Niño events often result in a weak Atlantic Ocean hurricane season; La Nina events can spell drought, even for normally dry California.

Factors that Influence Climate
There are lots of factors that influence our climate
Elevation or Altitude effect climate Normally, climatic conditions become colder as altitude increases. “Life zones” on a high mountain reflect the changes, plants at the base are the same as those in surrounding countryside, but no trees at all can grow above the timberline. Snow crowns the highest elevations.
Prevailing global wind patternsThere are 3 major wind patterns found in the Northern Hemisphere and also 3 in the Southern Hemisphere. These are average conditions and do not essentially reveal conditions on a particular day. As seasons change, the wind patterns shift north or south. So does the intertropical convergence zone, which moves back and forth across the Equator. Sailors called this zone the doldrums because its winds are normally weak.
Latitude and angles of the suns raysAs the Earth circles the sun, the tilt of its axis causes changes in the angle of which sun’s rays contact the earth and hence changes the daylight hours at different latitudes. Polar regions experience the greatest variation, with long periods of limited or no sunlight in winter and up to 24 hours of daylight in the summer.
TopographyThe Topography of an area can greatly influence our climate. Mountain ranges are natural barriers to air movement. In California, winds off the Pacific ocean carry moisture-laden air toward the coast. The Coastal Range allows for some condensation and light precipitation. Inland, the taller Sierra Nevada range rings more significant precipitation in the air. On the western slopes of the Sierra Nevada, sinking air warms from compression, clouds evaporate, and dry conditions prevail.
Effects of GeographyThe position of a town, city or place and its distance from mountains and substantial areas of water help determine its prevailing wind patterns and what types of air masses affect it. Coastal areas may enjoy refreshing breezes in summer, when cooler ocean air moves ashore. Places south and east of the Great Lakes can expect “lake effect” snow in winter, when cold air travels over relatively warmer waters.
In spring and summer, people in Tornado Alley in the central United States watch for thunderstorms, these storms are caused where three types of air masses frequently converge: cold and dry from the north, warm and dry from the southwest, and warm and moist from the Gulf of Mexico - these colliding air masses often generate tornado storms.
Surface of the EarthJust look at any globe or a world map showing land cover, and you will see another important factor which has a influence on climate: the surface of the Earth. The amount of sunlight that is absorbed or reflected by the surface determines how much atmospheric heating occurs. Darker areas, such as heavily vegetated regions, tend to be good absorbers; lighter areas, such as snow and ice-covered regions, tend to be good reflectors. The ocean absorbs and loses heat more slowly than land. Its waters gradually release heat into the atmosphere, which then distributes heat around the globe.
Climate change over timeCold and warm periods punctuate Earth’s long history. Some were fairly short; others spanned hundreds of thousands of years. In some cold periods, glaciers grew and spread over large regions. In subsequent warm periods, the ice retreated. Each period profoundly affected plant and animal life. The most recent cool period, often called the “Little Ice Age,” ended in western Europe around 1850.
Since the turn of the 20th century, temperatures have been rising steadily throughout the world. But it is not yet clear how much of this global warming is due to natural causes and how much derives from human activities, such as the burning of fossil fuels and the clearing of forests.
Effects of Climate Change
How will climate change effect us, there are many factors that will be affected by climate change including rising sea levels, drought and loss of agricultural land.
Increasing temperatures caused by climate change will make the water of the oceans expand; ice melting in the Antarctic and Greenland will also contribute to the sea level. Sea levels could rise by as much as 25 to 50 cm, by 2100. Greater sea levels will threaten the low-lying coastal areas such as the Netherlands and Bangladesh, millions of areas of land will be at danger from flooding; causing people to leave their homes. Low lying areas in cities will be hugely affected by the rising sea.
Changes in weather will affect many crops grown around world. Crops such as wheat and rice grow well in high temperatures, while plants such as maize and sugarcane prefer cooler climates. Changes in rainfall patterns will also affect how well plants and crops grow. The effect of a change in the weather on plant growth may lead to some countries not having enough food. Brazil, parts of Africa, south-east Asia and China will be affected the most and many people could be affected by hunger.
All across the world, there is a big demand for water and in many regions, such as the central and eastern Africa there is not enough water for the people. Changes in the climate will change the weather patterns and will bring more rain in some countries, but others will have less rain, generally dry areas will become drier and wet areas could become wetter.
As climate change takes place, our daily weather and normal temperatures will change, the homes of plants and animals will be affected all over the world. Polar bears and seals are a good example of animals that will be affected by climate change, they will have to find new land for hunting and living, if the ice in the Arctic melts, but the fact is more real that these species could become extinct.
Climate changes will affect everyone, but some populations will be at greater risk. Countries whose coastal regions have a large population, such as Egypt and China, may have to move whole populations inland to avoid flooding. The effect on people will depend on how well we can adapt to the changes and how much we can do to reduce climate change