Word Definition Translation affect to change or influence something. If something affects something else, it has an effect on it. air the mixture of gases surrounding the Earth that we breathe airfront a boundary line between two air masses. altitude the height of a place or thing above sea level (=the surface of the sea). anticyclone an area of high air pressure that produces calm weather with very little wind. antitrades winds that blow continuously away from the equator. ascend to rise into the air. atmospheric relating to or existing in the atmosphere round the Earth or round another planet. Beaufort Wind Scale a series of numbers from 0 to 12 that are used to show how strongly the wind is blowing. 0 means that there is no wind and 12 means that there is a hurricane. blizzard a storm with a lot of snow and strong winds. blow if wind or air blows, the air moves. boreal of or relating to the north. breeze a light wind. calm if the weather is calm, there is very little wind. Campbell-Stokes recorder an instrument used to measure the hours of sunshine each day. Celsius a system for measuring temperature that is part of the metric system, in which water freezes at 0 degrees and boils at 100 degrees. changeable tending to change suddenly and often. chart a list, drawing, or graph showing information in a way that is easy to understand. cirrus a type of thin cloud found very high in the sky. climb if a temperature, price, or the level of something climbs, it becomes higher. cloud a white or grey mass of very small drops of water in the sky cloudy full of clouds. cold front (op:warm front) the place where a moving mass of cold air meets a mass of warm air. Cold fronts usually cause heavy rain and they sometimes cause thunder. condense if gas or steam condenses, or if something condenses it, it changes into a liquid, usually when it becomes cooler. consequence a result or effect of something. convection the process by which the very small parts in a liquid or gas move and give out heat. convectional rain convectional rain occurs when air rises from a warm land surface. Coriolis Effect the reason that winds in the northern hemisphere are deflected to the right and winds in the southern hemisphere are deflected to the left due to the rotation of the Earth on its axis from west to east. Weather and climate cumulonimbus a mass of very tall thick cloud that usually brings rain and sometimes thunder. cumulus a large low white cloud that is round at the top and flat at the bottom. Cumulus clouds form at the lower levels of the atmosphere. cyclonic rain cyclonic rain is associated with low pressure systems. It forms at the fronts where warm and cold air masses meet. depresion 1. an area on a surface that is lower than the parts around it. 2. a large mass of air at low pressure that usually brings cooler weather and rain desert a large area of dry land that usually gets very little rain and has no permanent rivers, lakes etc. Very few plants or animals grow or live there. Most deserts are in hot regions, but there are some in very cold regions. desertification the process of land becoming so dry that it cannot be used for farming. This is often the result of human activities such as overgrazing and deforestation. drift to be pushed along very slowly by the movement of air or water. drizzle to rain in a very light way. drought a long period of time when there is little or no rain and crops die. dust bowl a region where there are a lot of dust storms because the soil has become dry from lack of rain. equator an imaginary line that goes round the Earth and divides it into the northern and southern hemispheres. exposed not protected from the weather. fertility 1 a woman's ability to have babies. 2 the ability of the soil to produce a lot of good crops or plants. fog a thick cloud that forms close to the ground or to water and is difficult to see through. Fog is thicker than mist. forecast a statement about what is likely to happen, based on available information and usually relating to the weather, business, or the economy (weather forecast). frost a thin white layer of ice that looks like powder and forms on things outside when the weather is very cold. gale a very strong wind. Gulf stream the current of warm water that flows from the Gulf of Mexico to the north and east across the Atlantic Ocean towards Europe. hail rain that freezes in the sky and falls to the ground as small balls of ice. hemisphere one half of the Earth. The northern hemisphere is the part of the world north of the equator, and the southern hemisphere is the part south of it. high pressure a large amount of force that the air produces in the atmosphere and that usually brings warm, calm weather. hurricane a violent storm with extremely strong winds and heavy rain. isobar a line on a weather map that connects places with the same air pressure. isohel a line on a weather map that connects places of equal sunshine. isohyet a line on a weather map that connects places of equal precipitation. isoline a line on a weather map. isotach a line on a weather map that connects places of equal wind speed isotherm a line on a weather map that connects places of equal temperature. landmass a continent or a large area of land that is surrounded by sea. latitude the distance of a point on the Earth from the equator, measured in degrees north or south. longitude magnetic pole a place near the North Pole or the South Pole that a compass points towards. mercury a silver liquid metal element that is used in thermometers. meteorology the scientific study of weather. mild mild weather is warm and pleasant, especially warmer than usual for the time of year. mistral a cold, dry wind from the north that is common in the south of France. moist slightly wet. monsoon a period of heavy rain in India and Southeast Asia nimbostratus thick low cloud that carries rain and covers all of the sky oasis a place in a desert where there is water and plants and trees grow observe to watch or study someone or something with care and attention in order to discover something. occluded an occluded front is the front formed when a cold front occludes (=overtakes and undercuts) a warm front. overcast with a sky completely full of clouds. ozone 1 a kind of oxygen that exists high in the Earth's atmosphere polar coming from, or relating to, an area near the North Pole or the South Pole. prairie a large flat area in central North America that is covered with grass and farms but has no trees. precipitation 1 rain, snow, hail etc. prevailing wind a wind that blows in a particular area at a particular time of year. rain gauge a piece of equipment used for measuring the amount of rain that falls. rain shadow a region that has little rain because it is protected by a mountain range in the direction of winds that carry rain. As the winds rise over the mountains they drop most of their water before reaching the other side. rainfall the amount of rain that falls in a particular area during a particular period of time. rainstorm a storm with a lot of rain. rainy season in some regions of the world, the season in which a lot of rain falls. ray an amount of light or heat from the sun. relative humidity the amount of water vapour in the air. renewable renewable energy and natural materials replace themselves by natural processes, so that they are never completely used up. resource something that you can use to help you to achieve something, especially in your work or study. rotate to move in a circle around a fixed central point, or to move something in this way. savanna a large flat area of land covered with grass in a warm part of the world. scarce if something is scarce, there is not very much of it. selva a dense tropical rain forest. sheltered a sheltered place is not affected by bad weather. sleet a mixture of snow and rain. smog polluted air that forms a cloud close to the ground. solar relating to the Sun, or coming from the Sun. spell a period when there is a particular type of weather. squall a storm that happens suddenly, especially at sea. starry a starry sky or night is one where a lot of stars can be seen in the sky. sticky sticky weather is hot and damp (=with a lot of water in the air). stratus flat grey cloud that is low in the sky. taiga an area of land situated below the tundra in the northern hemisphere. It has cold winters and warm summers with many coniferous trees. temperature a measurement of how hot or how cold a place or object is. Temperature is measured in degrees Celsius or degrees Fahrenheit, using the symbol °. thunder the loud noise that you sometimes hear in the sky during a storm. thunderstorm a heavy storm with thunder. tornado a very strong wind that goes quickly round in a circle or funnel (also called a twister). torrential torrential rain falls fast in large amounts. trade wind a wind that blows continuously towards the equator (=the imaginary line around the middle of the Earth). tropical used about weather that is very hot, especially when the air also feels slightly wet. typhoon a tropical storm with strong winds that move in circles. windy with a lot of wind.