Whether it is climate or not? Weather and Climate 1 Whether it is climate or not?

Today we will look at … What makes weather? How do we measure weather?

What is the weather? Weather is the condition of the air around us over a short period of time (from day to day)

The elements of weather Temperature (the amount of heat) Precipitation (water – rain, sleet, hail, snow) Wind speed Wind direction Clouds Air pressure Visibility (How far can you see?)

Temperature This is a measure of how hot or cold it is. We can tell this by looking at the clothes that people wear.

Precipitation Water in the air falls to the ground in one of several forms Rain Snow Sleet Hail But also ice and fog

Wind Speed This tells us how strong the wind is. We can get a good ideas of this by looking at smoke and trees.

Wind direction This is the direction from which the wind blows – it is measured by a wind vane

Cloud Type Clouds come in many shapes, sizes and heights – more about that tomorrow

Cloud Cover This is the amount of the sky covered by cloud. It is measured in eighths Clear sky 4/8 8/8 (Total cover)

Visibility This is the distance that can be seen. It is measured in metres.

Who else might find a forecast useful? Measuring Weather Who else might find a forecast useful? Why do we measure the weather? Weather can be described using terms such as wet or fine, warm or cold, windy or calm, so why is there a need to measure the weather? For most people, a description of the weather is adequate but for many businesses more detailed and accurate measurements are required. The science of studying weather is called meteorology. Weather scientists or meteorologists measure temperature, rainfall, pressure, humidity, sunshine and cloudiness and they make predictions and forecasts about what the weather will do in the future. This is important for giving people advance notice of severe weather such as floods and hurricanes – or even ‘Can I go out without my raincoat tomorrow?’

Measuring temperature The hotness or coldness of a substance is called its temperature and is measured with a thermometer. The ordinary thermometer consists of a hollow glass bulb attached to a narrow stem with a thread-like bore. The bulb is filled with liquid, If it is silver it is mercury If it is red it is alcohol The liquid in the tube expands when the temperature rises and contracts when the temperature falls. The amount of expansion and contraction is measured by a numbered scale.

Measuring temperature Most temperature scales today are expressed in degrees Celsius (°C), although you will sometime see Fahrenheit (°F) in use. The Celsius scale is fixed by two points, the freezing and boiling point of water, which at sea level are 0°C and 100°C respectively. The scale is then divided into 100 units.

Measuring Temperature The temperature tends to be highest around the middle of the day, when the sun is at its hottest – even if you cannot see it because it is cloudy The temperature is coldest during the night The difference between the daily maximum and the daily minimum temperature is the diurnal range. Why is temperature a factor of weather? What instrument measures temperature?

This one has a weather vane on it underneath. What does that tell you? Wind speed Wind is moving air. Wind can be measured by its speed and the direction from which it has come. The speed of the wind can be measured using a weather instrument called an anemometer. The speed can be recorded in many different units, including for example: miles per hour; kilometres per hour; metres per second Why is wind speed a factor of weather? What instrument is used to measure windspeed? This one has a weather vane on it underneath. What does that tell you?

Wind direction The direction of the wind is expressed as the point on the compass from where the wind is blowing. If a wind is blowing from the south, it is travelling northwards but is called a southerly wind. Wind direction can be measured in many different ways; using a weather vane or simply holding a light object such as a flag or ribbon. Why is wind direction a factor of weather? What instrument measures wind direction?

Wind direction Knowledge of wind direction is important for many people and activities. For example aircraft need to take off from the end of the runway which is going into the wind for extra lift at take-off Wind direction is of course very important for leisure activities such as sailing or windsurfing. Can you think of anything else where knowing the wind direction is important

Air pressure An instrument called a barometer is used to measure the pressure of air. When air is cooled it sinks towards the ground, the pressure increases and a high pressure is measured. When the air warms up it rises, the pressure is reduced and low pressure is measured.

Air pressure Why do we need to know about pressure? High pressure gives us clear skies Low pressure gives us cloudy skies and rain. Why is air pressure a factor of weather?

Precipitation What varieties of precipitation are there? Which types are NOT liquid? We measure precipitation using a ____ gage. Why is precipitation a factor of weather?

Weather is important to us At your table, draw a picture of a particular day. On the side, write down the weather conditions for your picture. Temperature (56°F - 40°F) Precipitation - Cloudcover Windspeed - Wind direction 5 Air pressure L