This paper evaluates models for simulating isoprene and monoterpene emissions from plants, focusing on their sensitivity to light and temperature. Isoprene emissions increase with photosynthetically active radiation (PAR) up to a saturation point of 700-900 μmol m⁻² s⁻¹ and rise exponentially at leaf temperatures below 30°C. Emissions continue to increase with higher temperatures until a maximum is reached around 40°C, after which they rapidly decline. A simple exponential relationship between emission rate (E) and leaf temperature (T) is given by E = Es [exp(β(T - Ts))], with β estimated at 0.09 K⁻¹ for all plants and monoterpenes. A model (G93) was developed to simulate these variations, incorporating both PAR and temperature effects. The model performs well for various plant species and accurately predicts diurnal variations in isoprene emissions within 35%. Monoterpene emissions are influenced by leaf temperature, with a simple exponential relationship between emission rate and temperature. The coefficient β for monoterpene emissions ranges from 0.057 to 0.144 K⁻¹, with an average of 0.09 K⁻¹. The model (equation 5) was evaluated for its ability to simulate monoterpene emissions, showing good performance with β = 0.09 K⁻¹. The study highlights the importance of accurately simulating biogenic hydrocarbon emissions for atmospheric models, as these emissions significantly influence atmospheric chemistry. The models developed in this study provide a good first-order approximation of isoprene and monoterpene emission rates, with recommendations for using β = 0.09 K⁻¹ for monoterpene emissions and model G93 for isoprene emissions. The results suggest that incorporating second-order effects into these models could improve their accuracy.This paper evaluates models for simulating isoprene and monoterpene emissions from plants, focusing on their sensitivity to light and temperature. Isoprene emissions increase with photosynthetically active radiation (PAR) up to a saturation point of 700-900 μmol m⁻² s⁻¹ and rise exponentially at leaf temperatures below 30°C. Emissions continue to increase with higher temperatures until a maximum is reached around 40°C, after which they rapidly decline. A simple exponential relationship between emission rate (E) and leaf temperature (T) is given by E = Es [exp(β(T - Ts))], with β estimated at 0.09 K⁻¹ for all plants and monoterpenes. A model (G93) was developed to simulate these variations, incorporating both PAR and temperature effects. The model performs well for various plant species and accurately predicts diurnal variations in isoprene emissions within 35%. Monoterpene emissions are influenced by leaf temperature, with a simple exponential relationship between emission rate and temperature. The coefficient β for monoterpene emissions ranges from 0.057 to 0.144 K⁻¹, with an average of 0.09 K⁻¹. The model (equation 5) was evaluated for its ability to simulate monoterpene emissions, showing good performance with β = 0.09 K⁻¹. The study highlights the importance of accurately simulating biogenic hydrocarbon emissions for atmospheric models, as these emissions significantly influence atmospheric chemistry. The models developed in this study provide a good first-order approximation of isoprene and monoterpene emission rates, with recommendations for using β = 0.09 K⁻¹ for monoterpene emissions and model G93 for isoprene emissions. The results suggest that incorporating second-order effects into these models could improve their accuracy.