Elements of weather are the various conditions that tell us what the atmosphere is like at a specific time and place. The main elements of weather are:

• Temperature — the measure of how hot or cold the air is
• Rain — droplets of water that fall from clouds
• Sunlight — natural light and energy from the sun
• Clouds — collections of tiny water or ice droplets floating in the air
• Wind — air moving from high pressure areas to low pressure areas
• Humidity — the amount of water vapour in the air
• Atmospheric pressure — the force created by the weight of air pushing down on Earth's surface

These elements can change within hours, days, or weeks. Sometimes the sky becomes cloudy, it becomes humid and hot, then it rains, and later the sun comes out again.

To understand weather changes, we must measure and record the weather elements using special instruments.

Temperature

Temperature is measured using a thermometer. There are two main types used in weather stations:

• Maximum thermometer — shows the highest temperature of the day. It contains mercury that rises when the air gets hotter and stays at the highest point even when the temperature drops.
• Minimum thermometer — shows the lowest temperature, usually read in the early morning. It contains coloured alcohol that falls when the air gets colder.

Both thermometers are kept in a white wooden box called a Stevenson screen, which protects them from direct sunlight so that readings are accurate.

Wind

Wind has two characteristics we measure: direction and speed.

• Wind vane — an instrument with an arrow that points to the direction the wind is coming from. The arrow is fixed on a rod with boards showing North, East, South, and West.
• Anemometer — an instrument with three or four cup-shaped arms that rotate when the wind blows. The faster the cups spin, the stronger the wind.

Humidity

Humidity is the amount of water vapour in the air, measured in percentage using a hygrometer. There are different types, including:

• Dry and wet bulb hygrometer — has two thermometers side by side. One is a dry thermometer, and the other has a wet cloth around it. The difference between the two readings helps calculate humidity.
• Digital hygrometer — shows the humidity level as a number on a screen, for example, 60%.

Rainfall

Rain is measured using a rain gauge. It has a funnel that collects rain water and directs it into a cylinder. The amount of rainfall is measured in millimetres. After rain stops, the water in the cylinder is poured into a measuring cylinder to check how much rain fell.

Sunlight

Sunlight is measured in hours using a sunshine recorder. It has a glass sphere and a card with hour marks. When the sun shines, it burns the card. We count the marks to know how many hours of sunlight there were.

Atmospheric Pressure

Atmospheric pressure is measured in millibars using a barometer. There are three types:

• Mercury barometer — a glass tube filled with mercury that rises or falls as pressure changes
• Aneroid barometer — a small metal box that expands and contracts
• Digital barometer — uses electronic sensors to give accurate readings

Clouds

Cloud cover is measured visually using the Oktas system. We imagine the sky divided into 8 equal parts, then count how many parts are covered by clouds:

• 0 Oktas — clear sky
• 1–2 Oktas — few clouds
• 3–4 Oktas — scattered clouds
• 5–7 Oktas — large part covered
• 8 Oktas — completely overcast

The height of clouds is measured using a ceilometer.

Imagine you are a weather observer at a school in Dodoma. In the morning, you check the maximum thermometer and it shows 32°C. Later in the evening, you check the minimum thermometer and it shows 18°C. This tells you that the temperature difference for that day was 14°C. You also check the rain gauge and find 5mm of rain collected. The wind vane points to the east, meaning the wind is blowing from east to west. The hygrometer shows 70% humidity.

By recording all these measurements, you can describe the weather for that day: warm temperature with a big range, light rain, easterly winds, and high humidity.

Farmers in Tanzania use weather information to plan their activities. For example, a rice farmer in Kilombero checks the rain gauge and weather forecast before planting. If the rainfall is low, the farmer may wait for more rain to ensure the crops will grow well. Knowing the weather helps farmers decide when to plant, harvest, or protect their crops from too much sun or heavy rain.