Measured by a thermometer/thermal probe
Temperature affects enzymes and therefore metabolism. Metabolic systems only work efficiently within relatively narrow temperature ranges. In extreme cases enzymes may denature.
Humidity is measured by a hygrometer.
It affects the rate of evaporation; the higher the humidity, the lower the rate of evaporation. The level of humidity determines the speed of evaporation and so controls the effectiveness of transpiration in plants and thermoregulation in animals.
Light intensity is measured by a light meter/sensor
Light is often the limiting factor of photosynthesis which affects the productivity of the whole ecosystem
pH is measured by a pH meter or chemical indicator test
It affects enzymes and metabolism can be disrupted if the conditions are too acidic or alkaline
Oxygen Concentration in Water
Is measured by an oxygen-sensitive electrode or chemical test
Oxygen is essential for aerobic respiration. Oxygen solubility in water is low and varies with tempearture; the lower the temperature, the more oxygen that will dissolve
Carbon Dioxide Concentration
Is measured by gas analysis
Carbon Dioxide is essential for photosynthesis and can be a limiting factor
Is measured by an anemometer
It affects rate of evaporation and cooling, so has an impact on transpiration in plants and thermoregulation in animals